Corrected SC_WARMER. Other cleanups

-Fixes bug 8044: http://hercules.ws/board/tracker/issue-8044-sorcerer-warmer/ TODO: Fix skill_unit_onout to work for skill_unit_timer_sub_onplace too.
- Cleaned some skill_unit_onout cases never reached.
- Removed icon for SC_WARMER.
Merge pull request #338 from csnv/unitcleanup

Corrected SC_WARMER. Other cleanups