Mouse handling system feels too complex

[Zooce]

I think I need to break up the logic in fn handle_mouse_events because it's doing a lot:

• check for and convert left mouse button clicks from window coordinates (bottom left origin) to world coordinates (center origin)
• check for marble selection (send event for highlighting)
• check for marble deselection (send event for removing highlighting)
• check for destination clicks

[Zooce]

be413aa5eeb0b14bac094ac413e8dd0003bd7ff4

This still may not be the best way to do things because this requires a check to ignore duplicate click events since the two states are accessing the mouse button input event reader, which seems to be creating two separate events so that each system reading them gets one.

[Zooce]

982bed163c19b6f19e15bc0f947e984abf31a2d7

I like what I've got now - one state, one mouse button input handler, destination click handler, and a highlighter.