* config herite from BaseInformation class

* _cfgimpl_ => _impl_
* optimpl_ => impl_
* properties/permissives are now set/frozenset
* validation raise ValueError if not valid, didn't return anything otherwise
* consistencies are now validate in setting and when deleting value
* ip/network with netmask consistency now works
* DomainnameOption now works
* if no validation, don't set cache for value
* symlinkoption: remove path (not used)

test/test_option_type.py

@@ -119,5 +119,5 @@ def test_with_many_subgroups():
     path = 'gc.subgroup.booltwo'
     homeconfig, name = config.cfgimpl_get_home_by_path(path)
     assert name == "booltwo"
-    getattr(homeconfig._cfgimpl_descr, name)
+    getattr(homeconfig.cfgimpl_get_description(), name)
     assert 'hidden' in setting[booltwo]