ZPE 1.8.11 is now available and is another small update in terms of the number of features but big in what the new features bring.
The first big new feature is support for infinite parameters. This is done within the definition with the double dot notation such as function x($y, $z ..). There is more in the documentation.
Reference functions have been completely redesigned, as have objects. With objects, there is a 2x performance increase whilst with reference functions, there is a much larger performance increase as well as a stability improvement. Reference functions can now be chained to each other much easier and this change requires much less code to do it.