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.

Include/asdl.h

@@ -0,0 +1,54 @@
+#ifndef Py_ASDL_H
+#define Py_ASDL_H
+
+typedef PyObject * identifier;
+typedef PyObject * string;
+typedef PyObject * object;
+
+typedef enum {false, true} bool;
+
+/* It would be nice if the code generated by asdl_c.py was completely
+   independent of Python, but it is a goal the requires too much work
+   at this stage.  So, for example, I'll represent identifiers as
+   interned Python strings.
+*/
+
+/* XXX A sequence should be typed so that its use can be typechecked. */
+
+/* XXX We shouldn't pay for offset when we don't need APPEND. */
+
+typedef struct {
+    int size;
+    int offset;
+    void *elements[1];
+} asdl_seq;
+
+asdl_seq *asdl_seq_new(int size);
+void asdl_seq_free(asdl_seq *);
+
+#ifdef Py_DEBUG
+#define asdl_seq_GET(S, I) (S)->elements[(I)]
+#define asdl_seq_SET(S, I, V) { \
+        int _asdl_i = (I); \
+        assert((S) && _asdl_i < (S)->size); \
+        (S)->elements[_asdl_i] = (V); \
+}
+#define asdl_seq_APPEND(S, V) { \
+        assert((S) && (S)->offset < (S)->size); \
+        (S)->elements[(S)->offset++] = (V); \
+}
+#else
+#define asdl_seq_GET(S, I) (S)->elements[(I)]
+#define asdl_seq_SET(S, I, V) (S)->elements[I] = (V)
+#define asdl_seq_APPEND(S, V) (S)->elements[(S)->offset++] = (V)
+#endif
+#define asdl_seq_LEN(S) ((S) == NULL ? 0 : (S)->size)
+
+/* Routines to marshal the basic types. */
+int marshal_write_int(PyObject **, int *, int);
+int marshal_write_bool(PyObject **, int *, bool);
+int marshal_write_identifier(PyObject **, int *, identifier);
+int marshal_write_string(PyObject **, int *, string);
+int marshal_write_object(PyObject **, int *, object);
+
+#endif /* !Py_ASDL_H */