Issue 4203: adapt sphinx-quickstart for windows

Hello,
for users on the windows platform, it could be of great help if the
sphinx-quickstart would be adjuste to their platform.
Here are my suggestions:
* create a batch file instead of the Makefile
    * make-docs.bat, contents: sphinx-build -a source build
* use "_" as default suggestion for the dotfiles.

Thanks for your great tool!