remove bad configuration caching (TODO: cache inside get_param).
move remove_empty_* functions out of config.c
add basic tests for remove_empty_units (no special units yet).
Eliminate dead code: FFL_NOTIMEOUT.
old feature for time-limited factions, not used anywhere.
test special treatment for spells in remove_empty_units.
test that empty factions are removed, but not monsters.
Merge pull request #39 from badgerman/master

Additional tests and elimination of dead code