Fix/cpp gen storing yaml (#900)

* fix: gen prettier c++ formatting(1)
* fix: c++ generator: special case for CWL-Expression type
* feat: c++-gen improved parsing/serialization

This now properly reads 'jsonldPredicate' and repsects the 'mapSubject',
'mapPredicate' and 'typeDSL' fields.

* refactor: cpp-gen: target node should be on the left
* feat: cpp-gen: load_document and store_document functionality
* feat: cpp-gen: store configuration, allows to generate some tags
* fix: cpp-gen: every is nested in 'cpp_gen' namespace
* fix: cpp-gen: transform list to map
* fix: cpp-gen: missing newline at the end of document
* fix: cpp-gen: detect common namespace
* fix: cpp-gen compatible code for clang and msvc
* fix: cpp-gen: update tests