Made active point and active spline behaviour more predictable on curves/surfaces:
* deselect all no longer leaves an active point
* the most recently added spline becomes the active one
* on successful duplicate/delete the active point and active spline are reset


git-svn-id: https://svn.blender.org/svnroot/bf-blender/trunk@61156 954f8c5b-7b00-dc11-b283-0030488c597c