fix issue208 and fix issue29 - avoid long pauses in traceback printing

by using the new getstatementrange() code of the py lib which uses
AST-parsing rather than the previous heuristic which had O(n^2) complexity
(with n = len(sourcelines))

- require new (in-dev) py version to

tox.ini

@@ -4,7 +4,7 @@ envlist=py26,py27,py27-nobyte,py31,py32,py33,py27-xdist,py25,trial
 indexserver=
     pypi = http://pypi.python.org/simple
     testrun = http://pypi.testrun.org
-    #default = http://pypi.testrun.org
+    default = http://pypi.testrun.org
 
 [testenv]
 changedir=testing
@@ -84,7 +84,7 @@ deps=py>=1.4.0
 
 [testenv:py33]
 deps=py>=1.4.0
-     nose
+     :pypi:nose
 
 [testenv:jython]
 changedir=testing