Make base_anim.nif take priority for biped creatures

Fixes the skeletal minion's WalkForward1h animation.
Don't add combat AI to player
Take actor's speed into account in stuck check

The Winged Twilight's walking animation was so slow that it incorrectly detects being stuck.
Remove redundant isHostile flag (Fixes #1652)
Reset player position when spawning in fallback cell
Adjust AiFollow running threshold to more closely match vanilla MW
Don't make guards fight non-aggressive creatures that are in combat

Ex. summoned creature that is helping in a fight.
Sheath weapon in all Ai packages except for AiCombat
Only show "target resists magic" message for spells cast by player
Cancel upper body animations when knocked down
Support loading text keys for objects without a skeleton

This means we can no longer map them to bone IDs, but they are unused anyway.

Required to load text keys from the default head models (such as Talk: Start/Stop and Blink: Start/Stop)
Implement mouth animation for NPCs based on say sound (Fixes #642)
Implement NPC eye blinking (Fixes #1721)
Fix normalizing sample values
Cache loudness vector in the buffer cache
Fix dangling MWWorld::Ptrs in enchanting dialog after loading save game (Fixes #1722)
Reset RefNum when copying an object (Fixes #1723)
Fix typo (RefId -> RefNum)
Implement collision script instructions (Fixes #1111)
Merge branch 'master' of https://github.com/OpenMW/openmw