PEP 343 -- the with-statement.

This was started by Mike Bland and completed by Guido
(with help from Neal).

This still needs a __future__ statement added;
Thomas is working on Michael's patch for that aspect.

There's a small amount of code cleanup and refactoring
in ast.c, compile.c and ceval.c (I fixed the lltrace
behavior when EXT_POP is used -- however I had to make
lltrace a static global).

Include/opcode.h

@@ -72,13 +72,12 @@ extern "C" {
 #define INPLACE_XOR	78
 #define INPLACE_OR	79
 #define BREAK_LOOP	80
-
+#define WITH_CLEANUP    81
 #define LOAD_LOCALS	82
 #define RETURN_VALUE	83
 #define IMPORT_STAR	84
 #define EXEC_STMT	85
 #define YIELD_VALUE	86
-
 #define POP_BLOCK	87
 #define END_FINALLY	88
 #define BUILD_CLASS	89