Implemented script commands StartCombat, StopCombat, GetTarget.

Also renamed one field of AIWander class because it's not longer
unknown.
printAIPackage: changed field name from Unknown to ShouldRepeat too.
MWScript: updated vmformat.txt, changed opcodes to fix sequence.

Opcodes for StartCombat, StopCombat, GetTarget now follow the last
previous opcode.
some junk removal
Merge remote-tracking branch 'sergeyshambir/startcombat'

Conflicts:
	apps/openmw/mwscript/docs/vmformat.txt
Knockdown / hit recovery improvements. Use formula and GMSTs from research wiki for knockdown determination. Hand-to-hand automatically knocks out when fatigue empty.
Handle fCombatKODamageMult and fCombatCriticalStrikeMult. Fix SelectWrapper Function_Detected.
Allow drain fatigue effect to reduce below zero
Automatically knock down when fatigue goes below zero
Fix skill progress not working
Increase sneak skill on successful pickpocket
Fix fatigue not restoring when waiting
Fix code duplication