Fix clippy lints and remove unneded borrows when logging or printing macros.
Use the 2021 Rust edition. To use current version of clap changes were adapted.
To supporte more than a single log level `log` and `env_logger` crates are used. For the application to support the different type of argument, the verbose argument definition was adapted.
pub
posix::*
This is in order to prepare also for SysV message queues.