Add alternate keyboard shortcut for Plan

The P shortcut key for Planning a task is a bit awkward, since if you're using your mouse right handed, then it's easy to use your left hand to hit any of the keys on the left side of the keyboard, but the P key is the right side so I actually end up using my mouse to click on the Plan button in a task instead of using the keyboard shortcut.
So I think some other key mapping on the left side of the keyboard would make more sense.