Prevent html encoding artifacts

Change .html() to .text() so that special html characters (ie, '<', '>') are not encoded when using this control in single select mode.
should be keydown for non-character keys' sake
add spacebar for checkbox toggle
when closing menu, focus the button
Fix memory leaks.

 - MultiSelect: Form events not being unbound on destroy.
 - Filter: Document events not being unbound on destroy.
 - Filter: Removed circular reference that prevented garbage collection.

Have not updated minified javascript!
prevent empty text in ui object when title attribute isn't provided to option tags
Merge branch 'master' of github.com:peytons/jquery-ui-multiselect-widget

# By Peyton Sherwood
# Via Peyton Sherwood
* 'master' of github.com:peytons/jquery-ui-multiselect-widget:
  when closing menu, focus the button
  add spacebar for checkbox toggle
  should be keydown for non-character keys' sake
Fixed unit test
Merge branch 'master' of github.com:tellibus/jquery-ui-multiselect-widget

# By tellibus
# Via tellibus
* 'master' of github.com:tellibus/jquery-ui-multiselect-widget:
  Identify correctly the files
  Add Arabic i18n files
  Add an option to specify separator string

Conflicts:
	src/jquery.multiselect.js
Updated demo to demonstrate correctness of the HTML escaping feature.
Added unit test for custom separator
Merge remote-tracking branch 'kander/master'