XML Data base classes

This bases clases will enalble DP to parse correctly formatted xml
files.

ListXMLData class is the base class - decent from this to handle
specific XML tags adn attributes

Add:
ListXmlData_Interface - interface class
ListXMLData - base class
package com.droidplanner.checklist

Remove:
pakcage com.droidplanner.chekclist.xml (wrong spelling)