[test] Add test for ProtrackerStudio loader

Signed-off-by: Claudio Matsuoka <cmatsuoka@gmail.com>
Handle memory allocation errors in PSM loader

Signed-off-by: Claudio Matsuoka <cmatsuoka@gmail.com>
[test] Add test for RealTracker loader

Signed-off-by: Claudio Matsuoka <cmatsuoka@gmail.com>
Fix memory violation in instrument name setting

Instrument names are limited to 32 bytes, enforce NUL string terminator
so maximum instrument size is set to 31 characters.

Also fix memory allocation error handling in RTM loader.

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