products if DateTime subclasses are mixed with ExtensionClasses.

numbers more easily.

use put2() in save_reduce() and save_inst() only if state is not a dictionary
removed put2() from save_tuple()

added cPickle_PyMapping_HasKey to replace leaking PyMapping_HasKey
lists and dictionaries are put in memo before saving their items
put2() added so that refcnt check isn't done in various cases

into object initializer, so it gets applied in all cases.

added check for empty tuples before memo check in save_tuple()

functions so that internal calls could be made without having to
go through PyArg_ParseTuple