Put the Ansible setup files in share directory

They are just an experiment, so they should not be cluttering up the
base directory.
Revert "Add autohighlight plugin"

This reverts commit 9cedcc223f52cf644e24f6887cffed0766925d03.

I've never used it.
Replace snippets directory with a plugin

Use a different repository to host all my customs snippets and
install it as a normal plugin.

I should have done it like this from the beginning ¬¬