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/Modules/md5module.c b/Modules/md5module.c
index 3c001ae..6856c68 100644
--- a/Modules/md5module.c
+++ b/Modules/md5module.c
@@ -56,7 +56,7 @@
 {
 	md5object *md5p;
 
-	md5p = PyObject_NEW(md5object, &MD5type);
+	md5p = PyObject_New(md5object, &MD5type);
 	if (md5p == NULL)
 		return NULL;
 
@@ -71,7 +71,7 @@
 md5_dealloc(md5p)
 	md5object *md5p;
 {
-	PyMem_DEL(md5p);
+	PyObject_Del(md5p);
 }