python - be: Fix handling of composite types (rendering instances).

Log Message:
-----------
Fix handling of composite types (rendering instances).

Also, if type_call gets a instance of the type as args, just return it. This is
handles a low-level case where the function may receive a composite or array
instance as args, instead of the usual Python tuple. (This is most likely to
occur on call/pl's return, where the result is given to the expectation)

Modified Files:
--------------
    be/src:
        type.c (r1.9 -> r1.10)
        (http://cvs.pgfoundry.org/cgi-bin/cvsweb.cgi/python/be/src/type.c.diff?r1=1.9&r2=1.10)