- Introduce a new D_xy tag which takes x_source and y_source
 - The two sources are attached to a DataConsistentcyGroup. Only If the
   consistency group signalizes a consistent state, the data is updated

It basically decorated the AutoPropertyDescription with the type which
is now in AutpPropertyDescription

Parse "type" attribute for normal properties

Bubble up the type to the parent class

so far, only scalars work and the meta data (macro pulse number etc. is missing)

changed interface of VariableMapper (list of descriptions instead of map because concept of 1:1 mapping does not work). Class compiles, but the rest of the lib incl. tests is not adapted yet

- Changes update to readLatest to allow consistent testing

changed variable mapper to actually produce spectra description, and the factory works out of the box. nice

added cherry picking test and improved exeption handling in case of missing attributes (not auto-tested yet)

changed PropertyDescription to be stored in a boost::any called doocsType, prepared comparison for it

hasHistory works as intended with location defaults. Code-cleaning needed, still tons of debug output in.

- parser accepts comments in xml file

stripped down the tests to work with the bit of current implementation that is there, to see that this is working and not breaking again

bool check in VariableMapper to implement new functionality. Tests still failing due to missing implementation