Better tags/keyword support for wallhaven

[mapleroyal]

Version of Variety you are using
0.8.18

Is your feature request related to a problem? Please describe.
Kind of. If you use several keywords, it drastically limits rather than increases the pool of results. Tags support would address this.

Describe the solution you'd like
Allow adding individual tags. Then:

• First: try to return wallpapers that have all the tags, but this may be very few or even none
• Next: expand the results pool to those that have SOME of the tags—sort by those with most tags to those with less

Thank you for considering this.