v0.19.0

• Change -d/--device option of tcconfig commands into a positional argument
  • e.g. tcset eth0 --rate 1Mbps
  • -d/--device option still can be used for backward compatibility
• Change tcset -f option to --import-setting option
• Add --color option to tcshow command
• Add support for Python 3.7
• Introduce colorized logging
• Fix choices for --shaping-algo option
• Bug fixes