Refactor and fix Amiga period range enforcing

Signed-off-by: Claudio Matsuoka <cmatsuoka@gmail.com>
[test] Add OpenMPT S3M FreqLimits test case

Signed-off-by: Claudio Matsuoka <cmatsuoka@gmail.com>
[test] Update for fixed Amiga period limits

Signed-off-by: Claudio Matsuoka <cmatsuoka@gmail.com>
Fix Amiga limits for notes with finetune

Amiga limits should obey finetunes, so the lowest period for a note with
a higher finetune is actually lower than the limit for a note without
finetune.

Signed-off-by: Claudio Matsuoka <cmatsuoka@gmail.com>
[test] Add OpenMPT MOD AmigaLimitsFinetune test case

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

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