Theme fix:

Node Editor and Sequencer were not using grid theme color, but 'back'.

This commit adds versioning to copy background color to grid. I do this
without increasing sub-version, which allows to add correct drawing when
the subversion has to go up anyway for something else.




git-svn-id: https://svn.blender.org/svnroot/bf-blender/trunk/blender@55535 954f8c5b-7b00-dc11-b283-0030488c597c