To porting setup scripts to python3, following utility functions/classes
introduced:
- run(): execute command line, returns return code
- out(): execute command line, returns stdout as string
- is_debian_variant() / is_redhat_variant() / is_gentoo_variant()
/ is_ec2() / is_systemd(): detect specific environment
- hex2list(): implement hex2list.py code as a function
- makedirs(): same as os.makedirs() but do nothing when dir is exists
- dist_name() / dist_ver(): alias of platform.dist()
- class systemd_unit: an utility to control systemd unit using systemctl
- class sysconfig_parser: reader/writer of /etc/sysconfig files
- class concolor: ANSI color escape sequences list
