Add an ftplugin for fish profile output files

[lilyball]

There's no standard extension for these files, so no ftdetect, but an ftplugin called fishprofile is defined that sets up tabstop and folding to make it easier to read/navigate these files.

When reading a fish profile file, run :setf fishprofile to turn on the plugin.

[dag]

What are "fish profile files"?