Organize features based on the catalog

[Balmung]

Right now (1.1.1) you place some assets and they are listed like this:

• Features
  • Feature 1
  • Feature 2
  • Feature 3

My idea is to utilize the tree structure more and organize assets by their set and category:

• Features
  • Basic Vegetation
    • SVG
      • Feature 1
      • Feature 2
      • Feature 3
  • Basic Terrain
    • SVG Mountains Medium
      • Feature 5
      • Feature 6
      • Feature 7

Or at least by their set:

• Features
  • Basic Vegetation
    • Feature 1
    • Feature 2
    • Feature 3
  • Basic Terrain
    • Feature 5
    • Feature 6
    • Feature 7

I do see that some people could be overwhelmed by this deeper structure but maybe it's possible to enable this via the settings.