[test] Add peristent vibrato test

Signed-off-by: Claudio Matsuoka <cmatsuoka@gmail.com>
Fix typo in changelog

Signed-off-by: Claudio Matsuoka <cmatsuoka@gmail.com>
[test] Add track volume slide tests

Signed-off-by: Claudio Matsuoka <cmatsuoka@gmail.com>
Fix track volume slide tests

Only perform slide if either volume slide up or volume slide down is
specified, not both.

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