* python/libvir.c: call the initialize entry point

* src/libvirt_sym.version: add initialize entry point
* src/libvirt.c: make sure we always initialize the lib
* python/tests/*.py: start updating exemple for exception
  handling as pointed by Jim Meyering
Daniel

libvir.c

@@ -269,6 +269,8 @@ initlibvirtmod(void)
     if (initialized != 0)
         return;
 
+    virInitialize();
+
     /* intialize the python extension module */
     Py_InitModule((char *) "libvirtmod", libvirtMethods);