[test] Add Fast Tracker 6CHN loader test

Signed-off-by: Claudio Matsuoka <cmatsuoka@gmail.com>
Fix OctaMED tempo setting in BPM mode

When using BPM mode in OctaMED MMD0/1/2/3 modules, keep the bpm value and
adjust the time factor accordingly.

Reported by Andreas Argirakis:

  Using version 4.2.1.

  http://files.exotica.org.uk/modland/?file=pub/modules/OctaMED%20MMD3/Silkworm/chemical%20graveyard%20%28noyz%20phaktah%20%27005%29.mmd3

  Playing the above song, the song is played too slow so the sample in the
  beginning is silent for a moment until the next one is played.

  http://files.exotica.org.uk/modland/?file=pub/modules/OctaMED%20MMD3/Neurodancer/arkanoid%2099.mmd3

  This song is also playing too slow.

  Tested both songs in OctaMED Soundstudio 1.03c on Amiga/WinUAE.

Signed-off-by: Claudio Matsuoka <cmatsuoka@gmail.com>
Adjust module type in MOD loader

Don't be too picky on tracker fingerprinting, and remember this should
be the module type and not the originating tracker.

Signed-off-by: Claudio Matsuoka <cmatsuoka@gmail.com>
Update changelog

Signed-off-by: Claudio Matsuoka <cmatsuoka@gmail.com>