Added support for multi-select comboboxes

Multi-select comboboxes fire the change event when un-selecting items in
the combobox which causes problems when we're only listening on the
select event with extjs4
Corrected indexOf for old browsers

indexOf is apparently not available on older browsers (IE), so utilize
the Ext.Array.indexOf function which handles browser compatability
problems for us.
Added htmleditor support

Support htmleditor by having it extend textfield with a listener on the
sync event to capture live changes