[Quest API] Add EVENT_COMBINE to Perl and Lua. (#1536)

- Exports $container_slot in Perl.
- Exports e.container_slot in Lua.

Allows you to perform events when clicking combine in a tradeskill container.

zone/event_codes.h

@@ -90,6 +90,7 @@ typedef enum {
 	EVENT_BOT_COMMAND,
 	EVENT_WARP,
 	EVENT_TEST_BUFF,
+	EVENT_COMBINE,
 	EVENT_CONSIDER,
 	EVENT_CONSIDER_CORPSE,
 	_LargestEventID