Remove usage of deprecated .message attribute of exceptions.

This fixes https://bugs.launchpad.net/ipython/+bug/407836.

The .message attribute of Exception is being deprecated in Python 2.6.
All new code should simply use args[0] for this purpose.  There are still
a few places that modules in external use this.  Hopefully these will
be updated soon.

IPython/core/iplib.py

@@ -1920,7 +1920,7 b' class InteractiveShell(Component, Magic):'
                 # SystemExit exception changed between Python 2.4 and 2.5, so
                 # the checks must be done in a version-dependent way.
                 show = False
-                if status.message!=0 and not kw['exit_ignore']:
+                if status.args[0]==0 and not kw['exit_ignore']:
                     show = True
                 if show:
                     self.showtraceback()

IPython/frontend/wx/ipythonx.py

@@ -6,11 +6,10 b' ipython.'
 try:
     import wx
 except ImportError, e:
-    e.message = """%s
+    e.args[0] = """%s
 ________________________________________________________________________________
 You need wxPython to run this application.
-""" % e.message
-    e.args = (e.message, ) + e.args[1:]
+""" % e.args[0]
     raise e
 
 from wx_frontend import WxController

IPython/kernel/error.py

@@ -127,7 +127,9 b' class TaskRejectError(KernelError):'
 class CompositeError(KernelError):
     def __init__(self, message, elist):
         Exception.__init__(self, *(message, elist))
-        self.message = message
+        # Don't use pack_exception because it will conflict with the .message
+        # attribute that is being deprecated in 2.6 and beyond.
+        self.msg = message
         self.elist = elist
   
     def _get_engine_str(self, ev):
@@ -147,7 +149,7 b' class CompositeError(KernelError):'
             return tb
   
     def __str__(self):
-        s = str(self.message)
+        s = str(self.msg)
         for et, ev, etb in self.elist:
             engine_str = self._get_engine_str(ev)
             s = s + '\n' + engine_str + str(et.__name__) + ': ' + str(ev)