Previously, a mixture of ~/.mono and ~/.config/.mono was used, which is confusing and does not follow the XDG directory standard. Configs should be folders in ~/.config and not be hidden.

I'm far from a Mono expert. This probably breaks a lot of things as-is, so I've marked it as [WIP], but at least it compiles fine. I mostly did this with grep and find/replace. I figured I'd open a pull request rather than an issue, to make an attempt at solving this, but if something is broken here I have no idea how to fix it. Feel free to take these changes and commit them separately if you wish.

See also: Directory specification, mono/monodevelop#7037, this video, this article.