Add equipment types to affixes

[fonsleenaars]

It's very useful for the affixes (pre- and suffixes) to list what equipment they apply to.

For the parser this means adding the equipment types (using the category names) to each affix.

For the website this means displaying this information, and allowing some basic filtering on the equipment types.

[LordVampir1983]

Similarly, if possible, I would like to know the chances of the appearance of certain affixes

[fonsleenaars]

That's possible, they're indexed just like loot tables so getting the chances shouldn't be a big challenge.

[fonsleenaars]

First setup is live on staging (https://staging.tq-db.net/affix/prefixes).

The chances are going to be tackled later, perhaps even per monster infrequent, unless it turns out the chance application is global for all non-unique/non-MI items. I'll get back on that (maybe make it a separate issue after 1.2.0 is released).