new cheaper constructor for DynamicPrintConfig from FullPrintConfig:

DynamicPrintConfig::full_print_config()
new cheaper constructors of DynamicConfig / DynamicPrintConfig from ConfigBase
Unit tests: ported test_model from upstream Slic3r, thanks @lordofhyphens
Unit tests refactored to use less autos and initializer lists for readibility,
DynamicPrintConfig is handled by value, not by shared pointer.

tests/fff_print/CMakeLists.txt

@@ -5,6 +5,7 @@ add_executable(${_TEST_NAME}_tests
 	test_data.hpp
 	test_flow.cpp
 	test_gcodewriter.cpp
+	test_model.cpp
 	test_skirt_brim.cpp
 	test_trianglemesh.cpp
 	)