add handling for common command-line utility functionality

[devoncarew]

Like:

• responding to --version
• responding to --help
• printing usage text (decorating the args usage text slightly)
• creating an ArgsParser object

Probably architected as an abstract template class?

@pq

[sethladd]

and usage integration

[pq]

@sethladd can you elaborate on what usage integration would look like?

[sethladd]

Depends on if cli_util is like a shell for command-line apps. Usage would like to know what command-line flags are used, so if cli_util is handling command-line flags, we should ensure the two work together.

[seaneagan]

Is the requested functionality any different than what's already available in both of the following?

• The unscripted package
• The command_runner library from the args package

AFAICT it's not yet possible to auto-add --version:

https://github.com/seaneagan/unscripted/issues/21

[sethladd]

Good question @seaneagan . Also, I'm not sure what the vision is for this package, or where this package would end and a stagehand template for a command-line app would start.