Add get methods first()/last() for Array, which allow for shorter code
(especially the method last())
Finished first draft of class CrsGraph. Functionality is minimal: one can
only add columnGIDs but not remove them. Access to graph data is granted
basically only after the graph has been closed and the column indices have
been converted to the local numeration (column map has been created).
A bunch of bug fixes (related to debug mode)
Starting to work on the CrsMatrix class
Starting to work on the parameter list classes and the xml file filter
Added some folders for the testing