swift234

Lexically distinguish prefix, postfix, and binary operators
and use this information as cues in the language.  Right now,
we do not accept things like "-- *i" because the prefix
operator is not correctly right-bound;  instead you have to
write "--(*i)".  I'm okay with that;  I did add a specialized
diagnostic recognizing operator-binary in a place where we're
expecting a potential operator-prefix.

Swift SVN r2161