definition files in geds3

The refactoring keeps going. I'm about to show the "load a map" feature, and then I'll have to show "how characters interact with the ground through properties".

Meanwhile, I'm digging what sort of additional definitions a "Behaviour Editor on DS" should read, and how that would be translated into .h files that convert the "level 2" scripts into plain "level 0 scripts" that can be parsed by the runtime engine on the DS. I'd allow e.g. BEDS to do more lookups in symbol tables while all symbols should normally be translated into values or expressions in level 0 when loading levels in a game.

Maybe you wonder "but what is level 1?" ... well, level 1 is what I'm doing right now with Bilou School Rush, with the C pre-processor expanding symbols for us so that I can write "$RUNLEFT->$RUNRIGHT on eDpad [D_RIGHT]" instead of "statl12->statr13 on event0 [v2 $20 &]".