Added fmt library in the project

fmt/src/os.cc

reading_machine/CMakeLists.txt

reading_machine/include/Action.hpp

reading_machine/include/Config.hpp

reading_machine/include/Transition.hpp

reading_machine/include/TransitionSet.hpp

reading_machine/src/Action.cpp

reading_machine/src/Config.cpp

reading_machine/src/Transition.cpp

reading_machine/src/TransitionSet.cpp