The test button section is getting a little crowded and will be more so when #3850 is done. We should organize it into categories or something.

Basic idea:

• Lifecycle
  • Dispose terminal
• Performance
  • Load test
• Styles
  • Test custom glyphs
  • Powerline symbol test
  • Add helper button to print a wide range of ansi colors #3850
• Decorations
  • Add decoration
  • Add overview ruler