Implemented "method(const none_t t)" pattern for all instances in "DataArray"
Implemented "method(const none_t t)" pattern for all instances in "DataTag", removed "remove*" methods
Corrected use of "method(const none_t t)" in "DataArray" to only exist for really optional types
Implemented "method(const none_t t)" pattern for all instances in "Dimensions"
Corrected errors in 'Dimensions' and 'DataTag'
Implemented "method(const none_t t)" pattern for all instances in "Properties"
Implemented "method(const none_t t)" pattern for all instances in "Sections"
Implemented "method(const none_t t)" pattern for all instances in "SimpleTag"
new tree_depth method in Section that gives the maximum levels below a
section
implemented Section::findDownstream(type) that is needed to find
related sections
implemented Section::findUpstream(type) helper function needed in find
related.
implementation of Section::findRelated(type) done!
result checks introduced because Section::findSection includes itself
into the search results.
Checks may be removed if we decide to exclude the starting section
from findSection
docstring  of Section::findRelated, and remove of old hasRelated
method stub
using filters for find related
DataSet: Add dataType() function to return the DataType

Function is based on the hdf5::data_type_from_h5() function.
[test] DataSet: Test new dataType() method
IDataArray: Add new getDataType() method and HDF5 impl.
DataArray: Add getDataType() method

Directly wired to IDataArray::getDataType()
[test] DataArray: Small check to test getDataArray()