[1.6.0] Implement hit object timing groups

[WilliamQiufeng]

Requires Quaver/Quaver.API#186

Changes:

• New Timing Group editing panel which allows:
  • Create/Delete timing groups
  • Rename timing groups
  • Change timing group color
  • Button to go to SV editing for the timing group
• SV Editor:
  • Now allows editing SVs in different scroll groups
• Editor view:
  • Hit objects can now be colored by timing group
  • The selected tab in SV editor is the current timing group we're working on
  • SV addition/deletion will take place in the selected timing group by default if the action's timing group parameter is null
  • The SV green lines will only show the SVs in the selected scroll group

Issues:

• Spam of events on color change
• SV plugins will take affect in the selected scroll group in SV Editor
• SV Lines will only show the SVs in the selected group

quaver-timinggroup-sv-2-compressed.mp4

[WilliamQiufeng]

Superseded by #4305 and #4306