Merge ast-branch to head

This change implements a new bytecode compiler, based on a
transformation of the parse tree to an abstract syntax defined in
Parser/Python.asdl.

The compiler implementation is not complete, but it is in stable
enough shape to run the entire test suite excepting two disabled
tests.
diff --git a/Python/traceback.c b/Python/traceback.c
index f40cfb4..b58e8ad 100644
--- a/Python/traceback.c
+++ b/Python/traceback.c
@@ -3,7 +3,7 @@
 
 #include "Python.h"
 
-#include "compile.h"
+#include "code.h"
 #include "frameobject.h"
 #include "structmember.h"
 #include "osdefs.h"