Support for Windows

[gschizas]

Out of the box, this script/custom command doesn't work in Windows (because an extensionless script can't be executable, I guess). I managed to fix this by these steps:

1. Make a cmd batch file
2. Create an alias

The batch file is very simple:

@echo off
py "%~dp0git-rewrite-author" %*

I saved it as C:\Program Files\Python37\Scripts\git-rewrite-author.cmd

The command for the alias was git config --global alias.rewrite-author "!C:/Program\ Files/Python37/Scripts/git-rewrite-author.cmd"

Once I figure out how to do these steps properly, inside setup.py, I'll do a pull request, but if someone has found this and wants it to work in Windows, these are the simple steps to follow.