* set sort order automatically to IndexOrder when changing order of items
* call onChanged when model is changed and then update view (needed when model is changed directly, not via view)
* support for digest signal so redundant updates can be avoided
* renamed rowCountChanged (signal) to modelDataChanged - detecting row count changes only was useless
* updated Doxygen / fixed typos
The following issues were fixed
* Fixed wrong/missing namespaces
* Fixed obvious typos in documentation
* Documentation not in sync with source code
refs #544