v0.4.1: closure toggle, to fix some confusion

This is a minor release to correct some documentation and a minor phoneme change.

[cl] was always used as a "toggle" for closures and not meant to always be used to labeling closures. It has been replaced with the [ct] phoneme to avoid confusion.
If you used [cl] before, you may need to remove and correct the usage.
Please refer to the LAB_HOWTO.txt file for correct usage.

Keep in mind the [ct] is an optional phoneme and you can go without using it in a dataset. You'll lose some control but the overall result will be about the same.

the [cl] phoneme is removed in this release. Thank you.