Checkpoint. 218 tests are okay; 53 are failing. Done so far:

- all classes are new-style (but ripping out classobject.[ch] isn't done)
- int/int -> float
- all exceptions must derive from BaseException
- absolute import
- 'as' and 'with' are keywords

Include/parsetok.h

@@ -23,7 +23,9 @@ typedef struct {
 
 #define PyPARSE_DONT_IMPLY_DEDENT	0x0002
 
+#if 0
 #define PyPARSE_WITH_IS_KEYWORD		0x0003
+#endif
 
 PyAPI_FUNC(node *) PyParser_ParseString(const char *, grammar *, int,
                                               perrdetail *);