Custom Directory& free space check

Hi, I've altered the install script, and the launcher bat to use a custom directory.

If you use a custom directory, it creates a config file, in the .babun folder, and the launcher then reads this, if it exists and calls the exe from it's custom directory.

Free space is checked now also (had to invoke powershell though, as numbers are too big for .bat).

There are still some issues related to other install scripts (like the vim profile file, which works with a manual install), and the babunrc file is created with wrong permissions?  It gets an error when launching.

Anyway, it is a long way towards greater portability and USB installs etc.