Log Message:
fasttracker2: update to b132

Changes since b130:

Beta #132 - 29.01.2019
- Fixed a bug where the sampling position line in smp. ed. could be drawn
  wrongly for a split second when switching between samples you're jamming.
  (samples, not instruments).
- Code cleanup

Beta #131 - 26.01.2019
- The linear interpolation routine in the audio channel mixer has been
  replaced with quadratic interpolation. This shouldn't cut off as much treble
  in the sound as linear interpolation. Though it comes with a price:
  The audio channel mixer requires slightly more CPU power, but it's still a
  relatively fast mixer. If you listen closely to songs with a lot of treble,
  you'll (hopefully) hear that they feel more life-like than before.
  Please note that this makes a minor difference, don't expect a lot!
- Fixed a bug where the mouse cursor could be stuck in busy mode (thus
  blocking the program) when certain errors happened during loading/saving.
- Saving an instrument now uses half the amount of RAM as before.