Calculate priority from MIME types of same family

[janko]

Some MIME types are in the same family, but their #simplified values aren't the same. One such example are "text/comma-separated-values" and "text/csv" MIME types. The former is obsolete and unregistered, while the latter is not obsolete and registered, but mime-types would still rank "text/comma-separated-values" higher because it just looks at the alphabetic order.

We check whether MIME types are belong to the same family by checking whether they have common extensions.

Fixes #131.

[halostatue]

This looks like a clean interim solution, but I’m not sure if it’s the correct solution. Let me think on this for a day or so.

[janko]

@halostatue Have you maybe decided about this one?

[halostatue]

I’m going to merge this. I worry that the & operator will be fairly expensive for this call. I think I’m going to need to do some rethink on some of this for future versions. It feels like a lot of these could be pre-computed into some sort of common value that would make comparison much easier.