This PR sets the default value of `OMF_CONFIG` variable in
framework init.fish file. The variable can still be overridden by
the user by setting it on `~/.config/fish/config.fish file`.
This is in preparation to rewriting install script in plain fish,
which will ditch config template and stop replacing `config.fish`
contents in favor of just appending Oh My Fish startup.
This variable records the value of $PATH environment variable before
oh-my-fish is sourced. When we "reload" the framework, we reset $PATH
with this recorded value so that we boot from a clean state.
Per conversation with @bpinto in Gitter.
There's no need for two separate directories. You don't have a `.git` and `.git-custom` folder, you just put your config in `.git` :)
The most straightforward interpretation of XDG basedir spec is that user configuration for omf would go in `~/.config/omf`, so let's put it there. The only question is whether omf-generated config (i.e. the `theme` file) should go there as well. By analogy with git, programmatically generated config should probably be merged in with user config. This also makes it so when a user clones their dotfiles to a new machine, both kinds of settings come with it.
