check all messages via print() and log.printerr()
clear expression with bool XOR
fix and reformat print()
fix printing messages
fix 'except' clause to be python3 compatible
Merge branch 'olf/check-all-messages' into develop
bump version to 0.3-dev
add subcommands 'help' and 'version' to replace options '-h' and '-v'
remove code for parsing options