new idMode of filterToolbar

!!! BREAKING  CHANGES !!!

The changes fixs the problem of id duplicates in the filter toolbar if
more as one grid with the filter toolbar exist on the same page and the
grids have *the same column names* in multiple grids.

The new option `idMode` allows to manages the way of id generation.
- The default value `idMode: "new"` creates safe ids based on the rule:
`"gs_" + gridId + columnName`.
- The option `idMode: "compatibility"` creates the ids based on another
rule: `"gs_" + idPrefix + columnName`. The rule would be helpful only if
one uses `idPrefix` options with *different* `idPrefix` values for every
grid. One can still have id duplicates if one don't use any `idPrefix`
option.
- The option `idMode: "old"` forces the usage of old rule for building
of the ids of the filter elements: `"gs_" + columnName`.

It's important to mention, that the current changes are important **only
if one uses some rule for input field directly in your code**. It's
recommended that you scan your code for the string `gs_` to be sure,
wthere you should make any changes in your code at all. If you will find
the places in your then you can either adjust the place of the code or
to use `idMode` with the value `"compatibility"` or `"old"` to revert
the rule of id building to the old one.

If you would like to change the default value of `idMode` option
globally to the value `idMode: "compatibility"` for example, you can
include the following code *before* call of `filterToolbar` method (for
example directly at the beginning of you code):
```JavaScript
$.jgrid = $.jgrid || {};
$.jgrid.search = $.jgrid.search || {};
$.jgrid.search.idMode = "compatibility"; // or "old" instead of default
"new", which creates safe id values
```

css/ui.jqgrid.css

@@ -1,6 +1,6 @@
 /**
  * jqGrid 4.13.1-pre - free jqGrid: https://github.com/free-jqgrid/jqGrid 
- * Date: 2016-03-07
+ * Date: 2016-03-08
  */
 
 /* Grid */

js/grid.base.js

@@ -8,7 +8,7 @@
  * Dual licensed under the MIT and GPL licenses
  * http://www.opensource.org/licenses/mit-license.php
  * http://www.gnu.org/licenses/gpl-2.0.html
- * Date: 2016-03-07
+ * Date: 2016-03-08
  */
 //jsHint options
 /*jshint eqnull:true */

js/grid.custom.js

@@ -235,6 +235,7 @@
 						stringResult: false,
 						groupOp: "AND",
 						defaultSearch: "bw",
+						idMode: "new", // support "old", "compatibility", "new"
 						searchOperators: false,
 						resetIcon: "x",
 						applyLabelClasses: true,
@@ -253,7 +254,18 @@
 					dataFieldClass = getGuiStyles.call($t, "filterToolbar.dataField"),
 					currentFilters,
 					getId = function (cmName) {
-						return "gs_" + p.idPrefix + cmName;
+						var prefix = "gs_";
+						switch (o.idMode) {
+							case "compatibility":
+								prefix += p.idPrefix;
+								break;
+							case "new":
+								prefix += p.id + "_";
+								break;
+							default: // "old"
+								break;
+						}
+						return prefix + cmName;
 					},
 					getIdSel = function (cmName) {
 						return "#" + getId(cmName);

js/jquery.jqgrid.src.js

@@ -8,7 +8,7 @@
  * Dual licensed under the MIT and GPL licenses
  * http://www.opensource.org/licenses/mit-license.php
  * http://www.gnu.org/licenses/gpl-2.0.html
- * Date: 2016-03-07
+ * Date: 2016-03-08
  */
 //jsHint options
 /*jshint eqnull:true */
@@ -8827,6 +8827,7 @@
 						stringResult: false,
 						groupOp: "AND",
 						defaultSearch: "bw",
+						idMode: "new", // support "old", "compatibility", "new"
 						searchOperators: false,
 						resetIcon: "x",
 						applyLabelClasses: true,
@@ -8844,11 +8845,22 @@
 					highlightClass = getGuiStyles.call($t, "states.select"),
 					dataFieldClass = getGuiStyles.call($t, "filterToolbar.dataField"),
 					currentFilters,
-					getId = function (cmName) {
-						return "gs_" + p.idPrefix + cmName;
+					getFiledId = function (cmName) {
+						var prefix = "gs_";
+						switch (o.idMode) {
+							case "compatibility":
+								prefix += p.idPrefix;
+								break;
+							case "new":
+								prefix += p.id + "_";
+								break;
+							default: // "old"
+								break;
+						}
+						return prefix + cmName;
 					},
-					getIdSel = function (cmName) {
-						return "#" + getId(cmName);
+					getFiledIdSel = function (cmName) {
+						return "#" + getFiledId(cmName);
 					},
 					parseFilter = function () {
 						var j, filters = p.postData.filters, filter = {}, rules, rule,
@@ -8889,7 +8901,7 @@
 						var sdata = {}, j = 0, sopt = {};
 						$.each(colModel, function () {
 							var cm = this, nm = cm.index || cm.name, v, so, searchoptions = cm.searchoptions || {},
-								$elem = $(getIdSel(cm.name), (cm.frozen === true && p.frozenColumns === true) ? grid.fhDiv : grid.hDiv),
+								$elem = $(getFiledIdSel(cm.name), (cm.frozen === true && p.frozenColumns === true) ? grid.fhDiv : grid.hDiv),
 								getFormaterOption = function (optionName, formatter) {
 									var formatoptions = cm.formatoptions || {};
 									return formatoptions[optionName] !== undefined ?
@@ -9010,7 +9022,7 @@
 						var sdata = {}, j = 0, nm;
 						trigger = (typeof trigger !== "boolean") ? true : trigger;
 						$.each(colModel, function () {
-							var v, cm = this, $elem = $(getIdSel(cm.name), (cm.frozen === true && p.frozenColumns === true) ? grid.fhDiv : grid.hDiv),
+							var v, cm = this, $elem = $(getFiledIdSel(cm.name), (cm.frozen === true && p.frozenColumns === true) ? grid.fhDiv : grid.hDiv),
 								isSindleSelect, searchoptions = cm.searchoptions || {};
 							if (searchoptions.defaultValue !== undefined) { v = searchoptions.defaultValue; }
 							nm = cm.index || cm.name;
@@ -9270,7 +9282,7 @@
 											}
 
 											if (soptions1.defaultValue !== undefined) { $select.val(soptions1.defaultValue); }
-											$select.attr({ name: cm1.index || cm1.name, id: getId(cm1.name) });
+											$select.attr({ name: cm1.index || cm1.name, id: getFiledId(cm1.name) });
 											if (soptions1.attr) { $select.attr(soptions1.attr); }
 											$select.addClass(dataFieldClass);
 											$select.css({ width: "100%" });
@@ -9306,7 +9318,7 @@
 									if (oSv) {
 										var elem = document.createElement("select");
 										elem.style.width = "100%";
-										$(elem).attr({ name: cm.index || cm.name, id: getId(cm.name) });
+										$(elem).attr({ name: cm.index || cm.name, id: getFiledId(cm.name) });
 										var sv, ov, key, k, isNoFilterValueExist;
 										if (typeof oSv === "string") {
 											so = oSv.split(delim);
@@ -9365,7 +9377,7 @@
 							case "text":
 								var df = soptions.defaultValue !== undefined ? soptions.defaultValue : "";
 
-								$("td", stbl).eq(1).append("<input type='text' class='" + dataFieldClass + "' name='" + (cm.index || cm.name) + "' id='" + getId(cm.name) + "' value='" + df + "'/>");
+								$("td", stbl).eq(1).append("<input type='text' class='" + dataFieldClass + "' name='" + (cm.index || cm.name) + "' id='" + getFiledId(cm.name) + "' value='" + df + "'/>");
 								$(thd).append(stbl);
 
 								if (soptions.attr) { $("input", thd).attr(soptions.attr); }
@@ -9403,7 +9415,7 @@
 								}
 								break;
 							case "custom":
-								$("td", stbl).eq(1).append("<span style='width:100%;padding:0;box-sizing:border-box;' class='" + dataFieldClass + "' name='" + (cm.index || cm.name) + "' id='" + getId(cm.name) + "'/>");
+								$("td", stbl).eq(1).append("<span style='width:100%;padding:0;box-sizing:border-box;' class='" + dataFieldClass + "' name='" + (cm.index || cm.name) + "' id='" + getFiledId(cm.name) + "'/>");
 								$(thd).append(stbl);
 								try {
 									if ($.isFunction(soptions.custom_element)) {
@@ -9495,7 +9507,7 @@
 						for (cmName in newFilters) {
 							if (newFilters.hasOwnProperty(cmName)) {
 								filter = newFilters[cmName];
-								$input = $(getIdSel(cmName));
+								$input = $(getFiledIdSel(cmName));
 								$input.val(filter.data);
 								$searchOper = $input.closest(".ui-search-input")
 										.siblings(".ui-search-oper")
@@ -9507,7 +9519,7 @@
 						for (i = 0; i < p.colModel.length; i++) {
 							cmName = p.colModel[i].name;
 							if (!newFilters.hasOwnProperty(cmName)) {
-								$(getIdSel(cmName)).val("");
+								$(getFiledIdSel(cmName)).val("");
 							}
 						}
 					}