Add support for loop mode release

[spessasus]

Adds support for the new "sample mode release" introduced by Polyphone 2.4

Resolves #1398

[sonarcloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
33.3% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarCloud

[derselbst]

Disclaimer: This is only my personal static code analysis - I haven't tested this yet.

IMO, the change is inaccurate because for two reasons:

• You're not implementing the 0.02s attack phase.
• Polyphone claims that the "playback begins with the release phase". But you implemented it in such a way that the voice plays back silently until the release phase begins (because of the dsp updates happening just before that). This behavior would be pretty equivalent to the delay phase, but I don't think this is the intended behavior by Polyphone.