SkullMarker

Cleaned up inconsistent behavior when in groups using Multi Mark Mode

• Marks should work correctly in marking the kill order without skipping every other mark, this is an issue created by the WoW Unit_target event triggering multiple times when in a party / raid / instance group
• Cleaned up Multi Mark Mode mark reset code to properly clean all the marks, this is handled but cycling each mark on your own character and then turning it off. Due to the nature of updating the marks for a party / raid / instance group, there is a slight delay on this happening in a party/raid/instance group so it will not happen invisibly there but will when solo if it is turned on for some reason.