Added spdlog for logging

include/spdlog/async.h

include/spdlog/async_logger-inl.h

include/spdlog/async_logger.h

include/spdlog/cfg/argv.h

include/spdlog/cfg/env.h

include/spdlog/cfg/helpers-inl.h

include/spdlog/cfg/helpers.h

include/spdlog/cfg/log_levels.h

include/spdlog/common-inl.h

include/spdlog/common.h

include/spdlog/details/backtracer-inl.h

include/spdlog/details/backtracer.h

include/spdlog/details/circular_q.h

include/spdlog/details/console_globals.h

include/spdlog/details/file_helper-inl.h

include/spdlog/details/file_helper.h

include/spdlog/details/fmt_helper.h

include/spdlog/details/log_msg-inl.h

include/spdlog/details/log_msg.h

include/spdlog/details/log_msg_buffer-inl.h