Change underscores to hyphens in command-line flags

[alexdewar]

So this is really a minor nit, but I feel like the long command-line flags should have hyphens not underscores in them, e.g. --config_dir should be --config-dir etc. It's obviously not particularly important (plus fixing it will technically be a breaking change), but it does look kinda odd to me (I'm not aware of other tools that use underscores, though I suppose there are probably some).

[AdrianDAlessandro]

Maybe convert to click?

[alexdewar]

Click's neat. It also supports setting console colours, so we could use this to colourise the log output. It also has its own progress bar implementation, so we could replace tqdm if we wanted.

[AdrianDAlessandro]

On hold until after v1.1.1 release

Also, opportunity to change CLI

• Remove -f flag and just make the file default first argument

[AdrianDAlessandro]

Maybe convert to click?

I've just heard of typer - which apparently is gaining traction over click