Limit MED4 sampled instrument octave range

Like MMD0-2, MED4 sampled instruments are limited to a 3-octave range.
Instead of changing the actual note event, we'll use the transpose
map for that instrument to keep notes within the valid range.

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

Signed-off-by: Claudio Matsuoka <cmatsuoka@gmail.com>
Fix crash in external command line assembly

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