Build in support for encoded accDescription (level, blah of blah etc) into IAccessibl...

Build in support for encoded accDescription (level, blah of blah etc) into IAccessible NVDAObject's description and positionInfo properties. However by default its not used as the 'hasEncodedAccDescription' class variable must be set to True. This has now been set to True for ITues items and qt treeView items. Specific encoded accDescription code has now been removed from these particular classes. Main reason for this change is that AIM also uses these encoded accDescriptions.