Merge pull request #540 from dariusk/master

Default selectable column option, minor optimization of canCellBeSelected
Added support for predefined group values to DataView.

New grouping info properties:
- predefinedValues - An array containing the grouping values for which
groups should be included even if they are empty.
- aggregateEmpty - Whether aggreggators should be run on empty groups.
Improved Checkbox editor ValueChanged behavior.

Checkbox editor was firing onCellChange event even when there was no change. This fixes that behavior and also returns a boolean on serialzeValue instead of the previous "checked" or undefined.
Remove usage on $.browser for jquery 1.9.0

jquery 1.9 has removed support for $.browser, use navigator.userAgent
instead
Merge pull request #543 from pzgz/jquery.1.9.0.fix

Remove usage on $.browser for jquery 1.9.0
incorporated suggestions by mleibman
Merge pull request #542 from wilcley/master

Checkbox editor ValueChanged event behavior fix