Reformatting plus step-wise execution

This update includes some reformatting of the code plus the addition of a feature that allows to execute just specific steps via a commandline option. This is helpful if for example you want to only rebuild an repackage kicad without going through the other steps of the scripts because you've got a slower system of internet connection (like i had during the last couple of days since I'm currently on vacation traveling through the U.S.A.). One might argue over the usefulness of this feature, but i definitely find it worth including.

The syntax is described in the script.