Vladimir Marangozov's long-awaited malloc restructuring.
For more comments, read the patches@python.org archives.
For documentation read the comments in mymalloc.h and objimpl.h.

(This is not exactly what Vladimir posted to the patches list; I've
made a few changes, and Vladimir sent me a fix in private email for a
problem that only occurs in debug mode.  I'm also holding back on his
change to main.c, which seems unnecessary to me.)
diff --git a/Python/traceback.c b/Python/traceback.c
index e1148cd..0b8157d 100644
--- a/Python/traceback.c
+++ b/Python/traceback.c
@@ -71,7 +71,7 @@
 	Py_TRASHCAN_SAFE_BEGIN(tb)
 	Py_XDECREF(tb->tb_next);
 	Py_XDECREF(tb->tb_frame);
-	PyMem_DEL(tb);
+	PyObject_DEL(tb);
 	Py_TRASHCAN_SAFE_END(tb)
 }