Implement a Table of Contents

[christopherbot]

Create a Table of Contents that is stickied to the top right (?) with all the system names.

Possible features:

• ToC is collapsable
• has a quick view of total/played/completed/favourite games
  e.g. GameCube (t: 47, p: 37, c: 12, f: 6)
  except maybe use icons instead of t/p/c/f
  total: search for collection icon?
  played: play icon
  completed: green checkmark
  favourite: gold star
• has a button to toggle all systems open/closed