[C2hs] A new kind of output marshallers *- (patch attached)

Hello When wrapping libraries that return error codes from functions a monadic output marshaller that does not return a value is very useful. This implements *- output marshallers that take the value and consume it, but don't return a result. This is used like: foo_error_t foo_something(random, arguments); type Err = {#type foo_error_t#} {#fun {`Foo', `Bar'} -> `()' handleError*- #} handleError :: Err -> IO () handleError ... - Einar Karttunen