python - be: Allow Oid_FromPyObject to implicity use a type's Oid Check

Log Message:
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Allow Oid_FromPyObject to implicity use a type's Oid
Check the result of PyNumber_Int and return InvalidOid on error.

This should be more stingy about what it will take, but for now it's convenient.

Modified Files:
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be/src:
conv.c (r1.3 -> r1.4)
(http://cvs.pgfoundry.org/cgi-bin/cvsweb.cgi/python/be/src/conv.c.diff?r1=1.3&r2=1.4)