[TS] MixDuration setter issues about spine-runtimes

[badlogic]

Sorry, this is a bug. I've pushed a new package to NPM. The old TrackEntry.mixDuration behaviour was restored. There's a new TrackEntry.setMixDurationWithDelay() method, which will allow you to recalculate the delay.

[smaren]

Hello, you named the method setMixDurationWithDelta (delta, not delay). Should it not function similar to the way it works in the LibGDX version? Currently, it subtracts delay instead of mix duration, and multiple calls to this function will still result in different results.
In any case, this fixes my issues, since we can set the mixDuration without any sideeffects.

[badlogic]

Uff, I didn't have my coffee yet. It should be called setMixDurationWithDelay. I fixed up both the name and implementation. Thanks for reporting!