New code structure: VFW choreographs - VFW tests updated
New code structure: VFW choreographs - GVF calls updated
New code structure: VFW choreographs - VFW implementation updated
lib/version_file_writer.js - bug fix to options validity tests
GeneratorManager - remove async_done from tests and impl
VFW impl - test for unexpected options properties
GeneratorManager impl - ctor validity checks from boolean 'is' to error-throwing 'check'
VFW impl, GM impl and tests - minor bug fixes
JsonCreator impl and tests to new VFW approach, other misc bug fixes
JsonCreator test - bug fix
VFW test - bug fix