Fix Trac #3155: better error message when -XRankNTypes is omitted
This patch sligtly re-adjusts the way in which the syntax of types
is handled:
* In the lexer, '.' and '*' are always accepted in types
(previously it was conditional). This things can't mean
anything else in H98, which is the only reason for doing things
conditionally in the lexer.
* As a result '.' in types is never treated as an operator.
Instead, lacking a 'forall' keyword, it turns into a plain parse error.
* Test for -XKindSignatures in the renamer when processing
a) type variable bindings
b) types with sigs (ty :: kind-sig)
* Make -XKindSignatures be implied by -XTypeFamilies
Previously this was buried in the conditonal lexing of '*'