Minor clean up of model code

* Match the arguments of GetRow
Major refactoring of CardsDataSource & friends

* UIDataViewList: Remove coupling of data source, database && paging
entirely; database is now standalone, paging is part of the data source.
  This resolves the need for compiling CardsDataSource.cpp from the
tests directory in nomlib's tree.

* CardsDataSorce: Implement paging feature into the model interface.

* libRocketDataGridTest: Add prototyping testing logic for
card selection actions.
Source files clean up