Merging changes from SL 4.8.7

[Roujo]

The goal of this PR is to share the work that's been done so that the fixes can also be shared, instead of multiple people working on it independently.

Known issues:

• General Issues:
  • [x] ThemePrefs.ini is filled with an empty preference section instead of filling in the default values
• Song Selection:
  • [x] The Music Wheel is pretty badly misaligned
  • [x] Steps aren't detected properly - there's a nil somewhere that makes the Grid in StepsDisplayList fail
  • [x] BPM display for selected song is too big
  • [x] Header contents are misaligned
  • [x] Measure breakdown under density graph is not calculated
  • [x] Marathon bubble is too large and misaligned
  • [x] Mode icon in the top bar is only visible for P1, P2 should replace it if we're logged in as P2
• Gameplay:
  • [x] Current score is shown over the density chart
• Score screen:
  • [x] QR pane is misaligned
  • [x] Extra high scores are showing on the bottom (what are these, anyway?)
• Session summary
  • [x] Most labels are the wrong size and position

[Sereni]

Hey, I think this is ready to be merged to dev and tested. Most screens look functional. WDYT?

[Roujo]

Sure, looks good to me! I should receive my replacement panels tomorrow - the previous ones cracked - so I'll give it a go then! =)