An experimental branch to see if changing flags to use bitsets instead of ints is helpful
More progress:
-All ship-related flags moved to ship_flags.h
-All flag references in ship.cpp moved to new system
-Created templated variant of parse_string_flag_list
-Created templated variant of flag_def_list
Merge branch 'bitset_flags' of https://github.com/scp-fs2open/fs2open.github.com into bitset_flags

Conflicts:
	code/ship/ship.h