Extract the IO function from DataArray into DataIO
DataIO: remove [get|set]DataDirect interface

and also make [get|set]Data as non-virtual functions
DataArray: mark io[Read|Write] as overriden
NDSize, Implement <, <=, >, >= operators + tests
ZonedIO: io to a DataArray constrained to a region
[test] tests for ZonedIO
retrieveData for MutliTags returns ZonedIO
adapted test for retrieveData
changed return type of retrieveData for Tags to ZonedIO
adapted tests
change return type of retreiveFeatureData to ZonedIO
changed return type, of retrieveFeatureData for multiTag
[DataArrayHDF] if read is called with no valid count it is set to a scalar in the correct dimensionality
[DataIO] quick fix for reading of scalar data

probably we need rethink which calss should take responsibility for setting
the correct count
adapted test for accesses without count.
Merge pull request #405 from jgrewe/dataio

 DataAccess via DataIO and ZOnedIO classes

Nice!