0.5.0

0.5.0: animated thumbnail setting, filter panel, marker editing, more links

• Add Settings → Animated thumbnails (Still by default): animated images
  are flattened unless turned on; entries record which form they hold, so
  switching refreshes only those. Clear the cache once on upgrade.
• Add a Filter panel to browse sections (rating, tags, performers, studios,
  organized, resolution); criteria use Stash's saved-filter format, so saved
  filters can be edited and saved back
• Add, edit and delete scene markers from the player and the scene editor
• Edit links of galleries, images and groups, and tags of performers/studios
• Keep the highlight in panels when the grid reloads; refresh scene
  markers after the player
• Update README; bump version to 0.5.0