Add information about getting to the base instance of the object in the debugger helper

Add information about getting to the base instance of the object in the debugger helper. Either this can be done with a Value.base() function (if this gets added) or the following example can be used:

def qdump__A(d, value):
   t = value.members(True)[0].type
   dptr, base_v = value.split('p{%s}' % t.name)
   d.putItem(base_v)