Updated documentation and fixed bug when using VMD in text mode

-check for Tk package before calling winfo

README.md

@@ -33,27 +33,29 @@ To install:
     e.g. change:
 
     - the file name `.vmdrc` _to_ `vmd.rc`
-    - the directory `$HOME` _to_ `%USERPROFILE%` (_e.g._ `C:\Users\myuser\vmd.rc`)
+    - the directory `$HOME` _to_ `%USERPROFILE%` ( _e.g._ `C:\Users\myuser\vmd.rc`)
     - the line 
 
 ```tcl
 set auto_path [linsert $auto_path 0 [file join $env(HOME) vmdplugins]]
 ```
 
-        _to_
+_to_
 
 ```tcl
-set auto_path [linsert $auto_path 0 {C:\vmdplugins}
+set auto_path [linsert $auto_path 0 {C:\vmdplugins}]
 ```
 
-        (substitute `C:\vmdplugins` with your plugin directory location)
+(substitute `C:\vmdplugins` with your plugin directory location)
 
 After installing, the vmdplugins directory should look like this:
-
-        vmdplugins/
-        +-- liquify/
-        |       +-- liquify.tcl
-        |       +-- pkgIndex.tcl
+
+```
+vmdplugins/
++-- liquify/
+|       +-- liquify.tcl
+|       +-- pkgIndex.tcl
+```
 
 Using the Plugin
 ------------------

liquify.tcl

@@ -259,9 +259,13 @@ proc Liquify::set_defaults {} {
 	set options(-savedir) [pwd]
 	set options(-savefile) ""
 	set options(-cube) 0
-	if {[winfo exists .liquify]} {
-		$Liquify::w.f2.y-e1 configure -state normal
-		$Liquify::w.f2.z-e1 configure -state normal
+	if {[catch {package present Tk} res]} {
+		puts "No X present"
+	} else {
+		if {[winfo exists .liquify]} {
+			$Liquify::w.f2.y-e1 configure -state normal
+			$Liquify::w.f2.z-e1 configure -state normal
+		}
 	}
 	set options(-adj_radii) 1.0
 	set options(-density) 1.0
@@ -462,6 +466,7 @@ proc Liquify::populate { gui } {
 	vmdcon -info "Calculating randomly packed density..."
 	set density [format "%.4f g/mL" [Liquify::calc_density]]
 	vmdcon "density: $density\n"
+	vmdcon "number molecules added: $tot_resid\n"
 
 	return 1
 }