20210606

• New tool for combining RB or GH2 Xbox 360 files into packs
• Fix game thumbnail of GH2 Xbox 360 files
• GH2 output picks a random GH2 character/guitar/venue for quickplay
• Fix Rock Band VENUE tracks always being replaced with a black background
• Fix invalid filenames caused by slash or backslash in song metadata
• Mix down drum stem configurations not supported by RB instead of failing
• Fix importing songs containing non-Latin-1 characters on Windows