-Added: CAUSEPAIN. Actors which deal damage (even if 0) while having this flag can cause other actors to trigger pain chances.
-Fixed: ALLOWPAIN should not trigger pain states if the damage is 0, but still allow for infighting to occur.
-Fixed: an unneeded logic call was processing damage modification when it was 0 to begin with.
- Added CPF_NOTURN flag for A_CustomPunch.
Merge branch 'cpf_noturn' of https://github.com/edward-san/zdoom