Blender Git Loki

=== Windows Installer ===
* Proper deletion of install dir - everything under it will be gone
* Ask if config/userdata can be removed and act accordingly. If selected, everything under user/config dir (BLENDERHOME) will be gone.
* The installer now will automatically update vc runtime

To be able to properly create an installer, you need:
- NSIS, and the MoreInfo plugin for NSIS. Make sure NSIS is in your path
- Set in your user-config.py BF_VCREDIST full path to the redist you have.

Note: this works only with SCons.