Change the source to a proper distribution

[qw3ry]

While the current install mechanism as mentioned in the README is good for a quick and dirty install, creating a distribution package will generally require the scripts to be installed in system directories.
Fish does provide mechanisms for this!

I'd recommend the following source structure:

• <function_name>.fish for each included function. This can be installed to pkg-config --variable functionsdir fish which points to /usr/share/fish/vendor_functions.d
• fishmarks.fish containing the aliases and the SDIR check. This can be installed to pkg-config --variable confdir fish (/usr/share/fish/vendor_conf.d)

This would clean up the installs and probably simplify the packaging process.
I am willing to provide a PR, if desired.

[techwizrd]

@qw3ry Are you still willing to provide a PR?

[qw3ry]

No, sorry. It has been a while and actually I'm not using fishmarks anymore. Feel free to close this