Add keyboard shortcuts for toolbar actions

[tonysyu]

QMenu.addAction has a key-sequence argument in it's signature, but QToolBar.addAction doesn't, so the initialization of keyboard shortcuts is a bit different.

[tonysyu]

Is there someone assigned as the gatekeeper for pyface? @rkern: Could you review or suggest someone for review?

[pankajp]

While this would be the correct thing to do, i suspect it may break many applications which use same action in toolbar and menubar, since now Qt would start showing ambiguous shortcut overload warnings.

[dpinte]

I suggest not to push this in 4.5.0 as the idea of 4.5.0 is to get a stable released version for the apps like Canopy that are currently working out of master.

[corranwebster]

I find that I often end up with two versions of an Action anyway - typically you want an icon for toolbar Actions, but don't for menu actions.