Pretty printing type application needs arity information

The pretty printer currently doesn't print nested applications correctly. As an example, if we have an application like SomeTyCon (Blah2 t1 t2 t3), It prints it as SomeTyCon Blah2 t1 t2 t3. This is to be expected, because TyCons don't carry their arity, so the pretty printer can't know when to wrap arguments in parenthesis.