Synchronized mode of color_print data to/from 3mf/amf

+ Code refactoring " CustomGCode extracted to separate namespace and file

src/libslic3r/CMakeLists.txt

@@ -114,6 +114,8 @@ add_library(libslic3r STATIC
     Line.hpp
     Model.cpp
     Model.hpp
+    CustomGCode.cpp
+    CustomGCode.hpp
     Arrange.hpp
     Arrange.cpp
     MotionPlanner.cpp