Blender Git Loki

* Removed a back pointer to a Scene (the "current" scene as in Blender
2.4x) from within Freestyle. Now Freestyle configuration parameters
are edited without relying on the notion of the current scene. This
resolved a few related issues as described below:

- A bug in Freestyle configuration management with respect to
multiple scenes was fixed. Now Freestyle configuration parameters
(e.g., style modules, ridges/valleys, suggestive contours) can be
specified for each render layer of each scene. Composition of
multiple render layers from different scenes should work as expected.

- A crash after undoing was fixed as well.

* Removed unused external Freestyle functions and global variables
from FRS_freestyle.h and FRS_freestyle.cpp.