python - be: Split off Array_FromPySequence to take an elmtoid instead

Log Message:
-----------
Split off Array_FromPySequence to take an elmtoid instead of the type tuple.

A small management improvement, but, of course, fails to address the more
serious issue of consistent instantiation methods.

Calling a type object will do something different than the Datum_From routines.

Modified Files:
--------------
be/include/pypg:
conv.h (r1.2 -> r1.3)
(http://cvs.pgfoundry.org/cgi-bin/cvsweb.cgi/python/be/include/pypg/conv.h.diff?r1=1.2&r2=1.3)
be/src:
conv.c (r1.5 -> r1.6)
(http://cvs.pgfoundry.org/cgi-bin/cvsweb.cgi/python/be/src/conv.c.diff?r1=1.5&r2=1.6)