DMN12 — Spaces in FEEL builtin functions

(from Bruce)
one barrier to FEEL implementation is parsing when both variables and built in function names contain spaces. Modelers and tools can elect not to use spaces in variable names but the functions are defined in the spec. Eliminating spaces in builtin function names would simplify parsing. E.g., distinct-values() instead of distinct values(). Xpath does it this way.

changing names of built-ins is not backward compatible

Changing names would not be backward compatible and hence is out of scope for an RTF; and there should be a higher bar to standardize multiple names for the same builtin.