Drop height to 0 when VAG ends.

Otherwise we will set it to !playing and never step the height.
Should fix Yu-Gi-Oh again.  Probably release before was miscalculated as
0 which is why it worked before.
Oops, remove extra PSPModel reference.
Correct a case where release rate was set negative.

Seems to be capped at INT_MAX like the others, oops.
Merge pull request #5387 from unknownbrackets/sas-minor

Fix recent ADSR regressions