audio/fasttracker2: Updates to v1.23

Changes since v1.22:

v1.23 - 29.04.2020
- Bugfix: The "default dirctories" paths in the config only worked for
  modules and not the other types (fixes GitHub issue #6).
- A much needed code refactoring of data structs. The code now also compiles
  with GCC 10.

(fox)