1. Add the new amalloc module, which (if enabled with

--enable-amalloc) replaced malloc and its ilk with
    versions that attempt to maintain a linked list of
    allocated blocks that can be printed to stderr with
    the `adump()` function.

2.  Clean up a couple more places where I leak memory
    during the first level parse.

3.  tweak cstring.h to try to chase down places where
    the C compiler might optimize EXPAND() into producing
    broken code.

mkd2html.c

@@ -35,6 +35,7 @@
 
 #include "mkdio.h"
 #include "cstring.h"
+#include "amalloc.h"
 
 char *pgm = "mkd2html";