update map format to use tileset indices for terrain
add utils/sctile: terrain tile extraction
add utils/grp.c: grp graphics extraction
rename rc to utils and extract to genspr
extract: update offsets and add more sprites
update asset extraction scripts and add a script for drone graphics
drw: correctly take into account simultaneous bounding on multiple borders
drw: fix not taking into account high scaling in boundpic
drw: reimplement compose using boundpic and drawpic's sematics
drw: fix vertical panning beyond map
drw: fix wrongly scaling pic width in broundpic
fs: fix not reading all rows and make loaddb semantics more consistent
drw: refactor drawpic, make it more comprehensible
ai: bound check setblk to avoid out of bounds with path map