Add missing AiFollow ActorId initialization (Fixes #1818)
SaveGameDialog: Allow deleting saves with keyboard (Delete key)
Set render queue group for projectiles (Fixes #1829)
Initial work on implementing corprus worsening effect
Move fast-forward of particle systems outside of OgreNifLoader (Fixes #1830)

Particle systems were being fast-forwarded before the skeleton base was attached, so particles without the LocalSpace flag would spawn at an incorrect position.
unloadUnreferencedMaterials: Properly unload materials instead of removing techniques
Implement saving/loading of corprus stats, remove redundant code
Make sure not to add duplicate viewports (Fixes #1832)

Wasn't a problem while testing reload() on linux. Maybe an implementation difference with Ogre's D3D rendersystem?
Purge blight should not remove corprus
Make Spells::mCorprusSpells private
Implement removal of corprus spells
Change player draw state when quick-selecting weapon or spell.
(Fixes #1828)
Merge remote-tracking branch 'miroslavr/corprus'
SaveGameDialog: use ComboBox accept event, not changePosition (improves keyboard navigation)
Need to change draw state if use'd item is in player's right hand.
Forgot to update comment.
getpcrank did not read the explicit reference in some cases (Fixed #1767)
fix for PCJoinFaction and for getPcRank without explicit reference
same fix for a couple of additional instructions
Refactor NIF cache

 - Remove broken cache locking mechanism

This was supposed to unload NIFFiles after a cell transition completes, but it was never working due to a mistake on the line if (--sLockLevel), should have been if (--sLockLevel == 0). Repairing this would increase load times (NIF files would have to be reloaded more frequently), so just removed it for now.

 - Decouple cache from NIFFile (now a new nifcache component)

 - Add API for future background loading

 - Provide a reliable way (SharedPtr) to hold on to loaded NIFFiles. This will be useful to avoid deep copies of keyframe and text key data, which is currently a performance bottleneck.