message: create version file
diff: @@ -10,6 +10,10 @@ set(GITTYUP_VERSION
  "${GITTYUP_VERSION_MAJOR}.${GITTYUP_VERSION_MINOR}.${GITTYUP_VERSION_PATCH}"
  )
  +# Write version to file so it can be used also from external, for example
  +# in the github manifest
  +file(WRITE "${CMAKE_BINARY_DIR}/Version.txt" ${GITTYUP_VERSION})
  +
  set(DEV_BUILD "" CACHE STRING "Mark this build as a development build with the given description")
  if (DEV_BUILD)
  