Remove all usages of println! and eprintln! from orbital code (except example)...
Fixes #44 (closed) Remove all usages of println! and eprintln! from orbital code (except example) and replace with log{info, debug, error}. Previous usages of println!() have been mapped onto to debug!() so the same output is produced (as log is initialized with Debug filter level). Previous usages of println!() (in obvious error branches) or eprintln!() have been mapped error!() to flag as errors. Initialize redox-log in main() with Debug level of filter (as env_log was before)