load land for non-base content files immediately
don't store esm readers for non-base content files
Remove PhysicsManager singleton and use shared_ptr instead.  Resolves the issue where sometimes destructors were called in an unexpected sequence resulting in a crash while exiting the application.
Re-insert existing DialInfo records when they are modified by another content file (Fixes #2170)
Initialise null shared_ptr
Another missed null shared_ptr conversion for gcc.
Do not delete physics objects if it was never created (e.g. preview window)
Move the destruction of global resources, being used by multiple documents, to the editor.
Do not destroy overlay if it was never created (e.g. due to an Ogre exception).
Merge remote-tracking branch 'scrawl/launcher'
Merge remote-tracking branch 'scrawl/master'
Queue screen fade operations invoked by scripts
Use a separate flag for references deleted by a content file (Fixes #2018)

The flag must be separate so as to not contaminate the user's savegame.

Fixes the following use cases that were broken before:

 - Content file edits a reference that was already deleted by a previously loaded content file -> reference must stay deleted
 - Changed or new content file deletes a reference that is already present in the user's savegame -> reference must be deleted
 - Said content file is disabled again - reference must be undeleted
memory leak fix
Merge remote-tracking branch 'scrawl/delete'
Move AiWander path finder to temporary storage (Fixes #2082)
Disable third person zoom feature by default due to usability issues (Fixes #2129)
Combat AI: Don't attempt to cast spells when impossible to succeed (Fixes #2059)
Implement Clamp mode for NiTexturingProperty (Fixes #2050)
Don't use transparency override if there's no transparency (rug fix for Bug #2050)