Make parsing of class declarations more conformant
Make parsing of class declarations more conformant

Previously jhc expected class declarations of the form:
class ... where list_of_type_sigs list_of_default_methods.
This patch fixes this and makes it more like Haskell98:
class ... where declaration_list

darcs-hash:20050920084753-e6152-4cbec7517f285c4eba06ff2266e397f9ea4760d1

kirbyfan64/jhc,kirbyfan64/jhc,kirbyfan64/jhc,kirbyfan64/jhc