Dropping leftovers from when battle.c wasn't all wired to the interface

Signed-off-by: shennetsind <ind@henn.et>
Hercules Renewal: skill.c complete

Added the last missing functions into the interface, all functions in skill.c are now wired to the interface.
http://hercules.ws/board/topic/237-hercules-renewal/

Signed-off-by: shennetsind <ind@henn.et>