Default paint context will be image paint if object is not in a paint mode. It solves not being able to tweak textures in the new texture context button system if an image editor is set up for painting and active object is in object mode.

git-svn-id: https://svn.blender.org/svnroot/bf-blender/trunk/blender@57624 954f8c5b-7b00-dc11-b283-0030488c597c