Start implementing new GUI

- Add assets folder
- Remove old top menu, and start implementing the new one
Add settings button to top menu & sort out a mouseLocked mess
Remove debug print
Bring back old view dragging
Implement inBdsMouse

inBdsMouse works like inBds2D, but automatically takes the mouse
coordinates as the pointer
Implement isHoverBottomMenu & inBdsMouseOffset

isHoverBottomMenu returns a boolean, which tells whether the mouse is
hovering over the bottom menu or not.
Remove commented code
Add fixture box selection
Implement threading for some tasks (EXPERIMENTAL!)

Some tasks (like dmx value checking and such) now no longer cause the
program to slow down, as they are computed on a seperate thread. Also
implemented SHIFT (additive mode) for the box selection tool.
More threading improvements
Merge from branch fixture-class
Start implementing new preset control UI
Move view drag & box selection to c_main_window.pde
Fix invokeFixturesDraw and other small changes
Remove debug print
implement to colorwheel
Work on new rear menu (preset UI)
More work on preset UI

Now uses the memoryMenu scroll value.
Fix mistake with threading multiexecute prevention
Now osc works!