Mods can now have their own lua files.

Furthermore, added game.dofile function, which executes a lua file from the current mod directory.
Fixed unused parameter warnings.
Only check creature attributes if we have a creature.
Update .pot
Fix slot machine so you don't win on average.
Merge branch 'master' of https://github.com/CleverRaven/Cataclysm-DDA
Merge branch 'fix_slot_machine' of https://github.com/vidarsk/Cataclysm-DDA into vidarsk-fix_slot_machine