Add an Emacs gitignore
Add cmd wrapper and stop on error

The wrapper is the best way of running this, as it will tell you if
something has gone wrong, and it will pass the right arguments to
Powershell.  This is based on this:
http://zduck.com/2012/powershell-batch-files-exit-codes/
Add a .gitattributes file

Use windows line endings everywhere.
Add a readme.
Search for Python installations in Registry

This means that it isn't necessary to have Python on the Path, or hard
code an installation directory.

It should probably have a way of prefering 32 bit or 64 bit
installations - but it isn't necessary for my usecase.
Extract variables to the top of the file.

Also adds some comments