Ambiguous associativity of noise operators

[braxbro]

Hello. I'm currently working on the ClaustOrephobic rewrite, and for this I'm writing a noise parser to put noise functions in a different, but still equivalent, format.

However, I've been struggling with some ambiguities in operator associativity, and would greatly appreciate it if the associativity of operators was included in the precedence list on the noise expression API documentation - as is, I have to either guess, or painstakingly devise ways to check each non-commutative operator beforehand.

[Bilka]

Exponentiation and the unary operators are right-to-left associative. The rest of the operators are left-to-right associative. Docs improved for 2.0.67, thanks for the note.