github:
fixes #6

for github:
fix #9

Do not rely on XDG settings being the defaults

The examples may now fail/act weirdly if XDG variables are not set, yet it's an overall benefit to change this.

excludesfile = .gitignore.d/$REPO_NAME is set on

* init
* clone
* seed-gitignore

Renamed the original INSTALL.md to EXAMPLES.md and created a new
INSTALL.md

Thanks to Gernot Schulz for writing most of the new content. It somewhat overlaps with INSTALL, but more docs are better either way.

Conflicts:
	INSTALL

Thanks to Gernot Schulz for most of the changes

As this is non-destructive, people may prefer it