Merge branch 'improve-sreader-version' into 'dev'

Improve ::ioAtoms::SReader and ::ioAtoms::SReader to find the correct 
data version without setting an XML parameter, only the 'patcher' tag is 
required to use the patch system.

When no version is defined in SReader and SWriter, the current version 
of MedicalData defined in fwMDSemanticPatch is used. This version can be 
overridden by the new method 'setCurrentVersion'. You can still define 
your own version and context.

Closes #117

See merge request FW4SPL/fw4spl!290