Add Miscellaneous Shortcuts To Viewfinder

[gselzer]

@marktsuchida I'd appreciate filling in things I missed:

Keyboard Shortcuts

• Moving stages - WASD or HJKL for XY stage? QE for Z stage?
• Snap/Live view

Mouse Shortcuts

• Double click to center view around mouse position
• Drag to move stage.

[marktsuchida]

I think that's all that we talked about, but you can take a look at MMStudio > Tools > Shortcuts for inspiration. There is Snap, Toggle Live, Toggle (current) Shutter, among others. The shutter is quite convenient on some scopes (where you can reach the keyboard while looking through the eyepiece). Not sure how many of these should be there when there is no way to customize them, though. The stage movement is probably more important than the others.

BTW probably not HJKL -- much as I like it, I don't think Vim users are a majority. Arrow keys are also an option for XY (but they may be more appropriate for associating with the axis slider(s)).

I would love it if there were visual feedback when one of these keys are pressed -- such as an arrow or chevron flashing in the middle of the image.

For the mouse stage shortcuts, good to have the option to disable.