Change some provider images. Add a few new images.

Add nzbs_in and nzb_is for custom providers to use.
Add network images for Esquire and Smithsonian.
Add a tweaked 6box for dark and light themes.
Reduce size of some images.
Fix article sorting for Coming Eps, Manage, Show List, and Trending Shows.

Increase article sorting strictness with a central helper function.
Merge pull request #64 from JackDandy/feature/FixArticleSort

Fix article sorting for Coming Eps, Manage, Show List, and Trending Shows
Merge pull request #63 from JackDandy/feature/AddImages

Change some provider images. Add a few new images.
Merge branch 'release/0.4.0' into develop