Knockdown check uses damage after armor reduction

Issue Description

Knockdown check uses damage after armor reduction, whereas research (https://wiki.openmw.org/index.php?title=Research:Combat#Knockdowns) shows it should use unmitigated damage.

Bug was introduced in 34eb3d48 when armor damage reduction was reordered into a lua script, prior to the knockdown check.

Relevant code is in onHit handlers of:

• apps/openmw/mwclass/npc.cpp
• apps/openmw/mwclass/creature.cpp
• files/data-mw/scripts/omw/combat/local.lua

System Information

• OpenMW Version:

  current master, ad0abfac