Update flexigrid.js

Update flexigrid.js to add a new property "fixCol" to fix a header column not to show in "Show/Hide" control menu and will be fix as it is initialized.

Just assign "fixCol" in the colModel as true and the column will not be in the Show/Hide panel.

Example :: {display: 'ID', name : 'id', width : 40, sortable : true, align: 'center', fixCol:true}


As I have discussed  in my stackoverflow profile.
http://stackoverflow.com/questions/16168446/frezze-or-fix-a-header-from-show-hide-menu-in-flexigrid