Syntax rules for `fun foo...` were so much simpler...

# announcements

[hastebrot]

Syntax rules for fun foo... were so much simpler. It just needed the tokens Keyword, Text and Name::Function and pop the state back to the root rules. fun <T...> foo(...) is much more complicated, because we need to copy a subset of the root rules for the tokens between Keyword (fun) and Name::Function.