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).

Lib/symbol.py

@@ -50,48 +50,50 @@ if_stmt = 292
 while_stmt = 293
 for_stmt = 294
 try_stmt = 295
-except_clause = 296
-suite = 297
-testlist_safe = 298
-old_test = 299
-old_lambdef = 300
-test = 301
-or_test = 302
-and_test = 303
-not_test = 304
-comparison = 305
-comp_op = 306
-expr = 307
-xor_expr = 308
-and_expr = 309
-shift_expr = 310
-arith_expr = 311
-term = 312
-factor = 313
-power = 314
-atom = 315
-listmaker = 316
-testlist_gexp = 317
-lambdef = 318
-trailer = 319
-subscriptlist = 320
-subscript = 321
-sliceop = 322
-exprlist = 323
-testlist = 324
-dictmaker = 325
-classdef = 326
-arglist = 327
-argument = 328
-list_iter = 329
-list_for = 330
-list_if = 331
-gen_iter = 332
-gen_for = 333
-gen_if = 334
-testlist1 = 335
-encoding_decl = 336
-yield_expr = 337
+with_stmt = 296
+with_var = 297
+except_clause = 298
+suite = 299
+testlist_safe = 300
+old_test = 301
+old_lambdef = 302
+test = 303
+or_test = 304
+and_test = 305
+not_test = 306
+comparison = 307
+comp_op = 308
+expr = 309
+xor_expr = 310
+and_expr = 311
+shift_expr = 312
+arith_expr = 313
+term = 314
+factor = 315
+power = 316
+atom = 317
+listmaker = 318
+testlist_gexp = 319
+lambdef = 320
+trailer = 321
+subscriptlist = 322
+subscript = 323
+sliceop = 324
+exprlist = 325
+testlist = 326
+dictmaker = 327
+classdef = 328
+arglist = 329
+argument = 330
+list_iter = 331
+list_for = 332
+list_if = 333
+gen_iter = 334
+gen_for = 335
+gen_if = 336
+testlist1 = 337
+encoding_decl = 338
+yield_expr = 339
 #--end constants--
 
 sym_name = {}