Bug fixes for envelopes, including crashes

[maiko3tattun]

• Fixed an edge case where the editor would crash if unexpected values were present in the envelope parameters (such as when using an older version of ustx) and the user performed an invalid operation.
• Added attack/release time delta to the scope of the phoneme reset menu in case the envelope knobs overlap and the values cannot be reset.
• Fixed a minor bug in the “Lengthen Crossfades” feature and improved the logic
• Improved the hit-test logic for overlap points