Rough implementation of optgroups (#8).
use classes to select child options, not '> *'
wrap optgroups in div
simplify optgroupwrapper into one template call
use [data-selectable] to indicate dropdown elements can be selected
style [data-selectable] correctly
Provide optgroup data to wrapper rendering function. Use "optgroup-header", "optgroup" instead of "optgroup", "optgroup-wrapper". Added docs. #8
allow optgroups to be passed in as an array
added optgroup example
add optgroup_columns plugin and example
set searchField in optgroup example
reposition or close dropdown when adding item
specify order of optgroups
Merge commit '06083990003505e7640caf7ccf9b62102b2d882e' into optgroups
Added "equalizeWidth" and "equalizeHeight" options to "optgroup_columns" plugin (#8).
Minor consistency updates.
Only highlight selectable options (don't highlight optgroup headers).
Added data-group attribute for class-independent selection + cleanup (#8).
Updated documentation (#8).
Updated demo.