Added frame rate limit, on chromebook, too slow anyway.
Added ability to select a unit and move.

A weird bug, I can select and move ok, but the time step only
increments when I'm moving the mouse or using the keyboard.  This
means the unit only moves under those circumstances as well.
Moved unit moving and time step outside event loop

This fixes the bug in previous commit, just check the pause state
after the event loop and we're good to go.  It was only moving
these if there was some event.