* Follow up to a942853.
* Removed ADJUST_SKILL_DAMAGE define so that the mapflag is always enabled.
* Cleaned up atcommand mapinfo and skill_damage mapflag interaction.
* Cleaned up atcommand mapflag to not allow setting of special mapflags that require extra arguments (Please use script command setmapflag).
* Using script command setmapflag for MF_NOSAVE will default to SavePoint.
* Using script command setmapflag for MF_PVP_NIGHTMAREDROP will default to normal official drop values.
* Exported constants for skill_damage mapflag types.
Thanks to @ecdarreola, @cydh, and @Lemongrass3110!
- Disabled by default on src/config/core.h. Uncomment '#define ADJUST_SKILL_DAMAGE' to enable this skill damage adjustment
- Added skill_damage_db.txt (thank Lilith for 'Manage Skill Damage')
- Added new mapflag: 'skill_damage'. Please read 'doc/mapflags.txt' for more details
*Fixed bugreport:8029 (thank exneval for testing and reporting) (Akinari)
*Follow-up 647f99f (Akinari)
*Follow-up 15074d8: optimized item_isNoEquip check parts
*and some mirror changes