Renamed SDL2.desc for case sensitive systems.
Added Engine::raiseDebugger() that raises the debugger.

This helps raising the debugger in code only when needed,
especially when raising from scripted code.
Force the update of a TextField on a Moviclipe init.

This sets the AABBs properly for the textfields, fixing
a bug which happens when the textfields are not updated,
but added to the state, having a wrong AABB.
Fixed building BaconBox on Linux.

The fixes in the engine will initialize OpenGL in the right order.

The fixes for SDL2_mixer may be setup-dependent, but disabling this
library should not affect anything with BaconBox.