New Song Buttons with Difficulty Ratings for Each Song.

Changes/Additions

• New song selection buttons that display song information and difficulty rating.
• Changed some difficulty estimate weighting to give more accurate results.

Bugs Fixed

• Fixed songs not loading correctly and causing a soft lock when switching from Featured to Custom.
• Fixed a bug when importing a custom song from the practice menu.
• Fixed another bug related to songs not loading correctly causing soft lock when switching from Featured to Custom.