state file name and line number in lua error messages

racer: if hog starts race without any weapon selected, select whatever is first

lua api: SetNextWeapon()

lua api: DismissTeam(teamname)

lua api: SetWeapon(ammoType)

fix broken speech bubble display in chat. caused by r1a6b9a98147c one line was forgotten when moving some code

more of the same

fix TryPlaceOnLand's ambiguity/messup wrt to making terrain indestructible (had boolean parameter for indestructible AND landflags parameters that could contain lfIndestructibly)

further WIP (better error messages)

placeSprite accepts any amount of landflags now; further WIP wrt cleanup/fixing