Fixed skill flagging (mostly related to SKILL_FLAG_REPLACED_LV_0 )

Adjusted value as to not conflict with the perm_granted flag
Special Thanks to Wildcard, malufett.
Also made pc_skillup rely on the change_level_2nd/3rd vars instead of hardcoded values, and added a pc_gainexp packetver check that'd otherwise cause map server warnings when within the range.

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