ENH: Expose functions for reproducing 3D view shortcuts

Before this, there was no simple way to ask programaticaly for the view
to reset the camera like it does when pressing the key pad shortcut keys.
Now the user can do this directly from python. This is potentially useful
for the scripted modules as well.

git-svn-id: http://svn.slicer.org/Slicer4/trunk@25651 3bd1e089-480b-0410-8dfb-8563597acbee