node data removed from template logic

a node's data field was previously used for (sane) template level logic, such as toggling of selection css class
node is now bound directly to template, and the data member is now used for data access only
removed debug statements
mutual exclusive seletion handling handled properly by ruler service

selection delegated to a named handler, as it should be
an ugly hack so that nodes properly handle inheritance of cost, this will be removed once a proper inheritance pattern is implemented
ugly hack for cost propagation when a node is added as a child