Expose more controls to the user

[jsiegle]

Currently, a number of important functions (such as camera focusing and stage translation) require modifier keys and/or middle mouse button scrolls/clicks. It's fine to keep these shortcuts, but there should also be buttons or drop-down menus that can be used instead.

[chronopoulos]

update: stage translation is now controllable via the Targeting Dialog (crosshairs button). camera focusing relies on ctrl+shift+scroll wheel - i will implement a dialog window to control this from the screen.

i believe all other keyboard shortcuts have buttons analogs, but let me know if i'm missing anything