Allow whitespace with --pointermap CSS

Any leading or trailing whitespace is now removed from the value for the `--pointermap` CSS property. This allows it to
act more like a standard CSS property where leading and trailing whitespace is not significant, and it allows the CSS
author to format their code more freely.

Fixes RPTools#2348.

src/main/java/net/rptools/maptool/client/ui/htmlframe/HTMLOverlayManager.java

@@ -191,7 +191,7 @@ HTMLOverlayPanel.mousePassResult getMousePassResult(int x, int y) {
     if (element == null) {
       return HTMLOverlayPanel.mousePassResult.BLOCK;
     } else {
-      String pe = (String) element.eval(SCRIPT_GET_POINTERMAP);
+      String pe = ((String) element.eval(SCRIPT_GET_POINTERMAP)).trim();
       if ("blockopaque".equals(pe)) return HTMLOverlayPanel.mousePassResult.CHECK_OPACITY;
       if ("block".equals(pe)) return HTMLOverlayPanel.mousePassResult.BLOCK;
       return HTMLOverlayPanel.mousePassResult.PASS;