Log Message:
fasttracker2: Update to b163

Changes since b162

Beta #163 - 29.07.2019
- SDL updated from v2.0.9 to v2.0.10
- Bugfix: Don't unmute channels when loading a new song (FT2 behavior)
- Bugfix: Disk Op. didn't list correct kB/MB/GB filesizes (1000 vs. 1024)
  + rounding upwards on kB/MB/GB sizes.
- The Trim screen is a bit cleaner looking now
- Instrument slots are now allocated as needed (FT2 behavior). This new
  behavior means little to the user, but makes it easier for me to port the FT2
  code more directly when it works like this. This also means that XMs are
  now saved exactly the same way FT2 does it, except for certain uninitialized
  instrument header fields (FT2 bug) being set to zero.
- Updated the help text