Improvements to command line interface

[merlinz01]

This PR uses click instead of argparse for the command line interface.

Benefits include:

• Ability to define global options
• Ability to define options with env var backup
• Builtin colorization for more attractive and readable output
• An Abort error to exit cleanly

[henadzit]

Thanks for the contribution!

Although I don't like the idea of adding dependencies to the project when it can be avoided. There is no need to have click, this can be achieved with argparse.

[merlinz01]

IMHO it's worth the single dependency for the increase in readability/maintainability, type safety, functionality, and user experience quality.

Aerich uses asyncclick which is an async-compatible fork of click.

[merlinz01]

OK, I've gotten it fairly similar without click dependency, with a few helper functions. See the updated code.