Support shift-click to select a range of capabilities

[johnbillion]

I recently needed to remove a large number of capabilities from a role, which meant clicking in each capability checkbox when editing the role.

It would be great if shift-click worked, so you could click the first checkbox and then shift-click the last to select all the checkboxes in between.

Core supports this behaviour on all of its list screens.

[justintadlock]

Definitely a good idea. This has been an annoyance for a while for me too.

[johnbillion]

Related: #65

[justintadlock]

Played around with this a bit today. Had a working solution but it conflicted with my onchange event when checking/unchecking boxes. The code there needs to be reworked.

I'm planning a complete JS overhaul in 3.0 and will handle it there.