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/svmodule.c b/Modules/svmodule.c
index 75f2023..99c6fa1 100644
--- a/Modules/svmodule.c
+++ b/Modules/svmodule.c
@@ -340,7 +340,7 @@
 		Py_DECREF(self->ob_svideo);
 		self->ob_svideo = NULL;
 	}
-	PyMem_DEL(self);
+	PyObject_Del(self);
 }
 
 static PyObject *
@@ -374,7 +374,7 @@
 {
 	captureobject *p;
 
-	p = PyObject_NEW(captureobject, &Capturetype);
+	p = PyObject_New(captureobject, &Capturetype);
 	if (p == NULL)
 		return NULL;
 	p->ob_svideo = self;
@@ -994,7 +994,7 @@
 {
 	if (self->ob_svideo != NULL)
 		(void) svCloseVideo(self->ob_svideo);
-	PyMem_DEL(self);
+	PyObject_Del(self);
 }
 
 static PyObject *
@@ -1026,7 +1026,7 @@
 {
 	svobject *p;
 
-	p = PyObject_NEW(svobject, &Svtype);
+	p = PyObject_New(svobject, &Svtype);
 	if (p == NULL)
 		return NULL;
 	p->ob_svideo = svp;