Add Extra / Nice-To-Have Filters

[ScuffedNewt]

Adds some filters around the site!
This is marked as ready, but ideally would be home to some discussion / conversation about areas that might need some filters!
Lorekeeper is a bit of a beast as is, but funnily enough, does not have a consistent coverage of filtering

Areas Added Thus Far:

• User and character inventories
• User submissions
• Loottables (admin panel)

[SpeedyD]

Looks good at first glance, will give this a more solid review (and likely approval) when I got more time ^^;;

[SpeedyD]

...yeah, I looked it over thoroughly and I STILL missed the fact that $artists wasn't defined. =_=;;

Eesh.. Good job catching and fixing that, Newt. Reapproved.

[itinerare]

Checking in with this one-- are you interested in adding more onto it, or should I just go ahead and merge?

[ScuffedNewt]

I didnt think of any more myself, and I don't think anymore where suggested, so I think this is fine to merge as-is and if more search filters are requested down the line it should be easy to add in another PR!

[itinerare]

Makes sense to me!