Fix for Node Editor tool "Find next/prev of same type".

This is the first half of the commit, it's going to be reviewed further.
It also depends on other work in node drawing (to not reshuffle order on
every select/activate).

At least it works quite nice for the shortcuts shift [ and shift ]




git-svn-id: https://svn.blender.org/svnroot/bf-blender/trunk/blender@55628 954f8c5b-7b00-dc11-b283-0030488c597c