Syntax-highlighting fixes for Haskell & Curry

By Bastian Holst.

Syntax-highlighting: names starting with import

In Haskell source files, the prefix 'import' in names has been
highlighted as a keyword. This is hereby fixed by asking for a
whitespace character after the word 'import'.

Syntax-Definitions: Comments in Haskell & Curry

Allow comments in import declarations in Haskell and Curry files.
These look quite similar because both languages share most of their
syntax.

REVIEW: 113363