Moved functions from niffile.cpp to where they belong.

Also cleaned up some #includes

Removed a few asserts.  Vector already throws an out_of_range error.
Convert niffile.cpp to use std::map instead of a custom search function.

I haven't profiled this, but it should speed things up a decent bit.
Merge remote-tracking branch 'miroslavr/master'
Show encumbrance preview when trading (Fixes #1793)
Remove unused numUnload
Remove wrong comment
Don't treat actors as following if another non-combat AiPackage precedes (Fixes #1843)
Fix potential infinite recursion in ActionTeleport (Fixes #1840)
Fix incorrect Speed value in ESM::MagicEffect (thanks Hrnchamd)
Knock out actors when fatigue base is 0 (Fixes #1847)
Open inventory when activating an unconscious actor (Fixes #1848)
Fix bad indentation
Use MyGUI clipboard events for MyGUI 3.2.1+ (Fixes #1846)

Note that only <= 3.2.0 and >= 3.2.1 are supported, any SVN version between them might still exhibit duplicate text pasting.
Don't pass key to input binder if it was consumed by text editor (Fixes #1845)
Implement multiple emitter nodes for NiBSPArrayController

The particles for the flame, frost and storm atronachs work correctly now.
Add version parsing to FindMyGUI.cmake
Require MyGUI version 3.2.1 and remove legacy code (Fixes #1528)
Allow user-created markers on local map (Fixes #1571)
Minor cleanup
Feature #1616: Body part record verifier