Add a flag that allows for compact output

[tbarusseau]

As of now, all commit messages seem to be spaced out:

    ci(CircleCI)!: Renamed main build job
    
    Renamed main build job from `build-base` to `base`
    
    BREAKING CHANGE: The `build-base` is now named `base`
    
    123

Allowing the user to generate a more compact message with -c/--compact would be neat:

    ci(CircleCI)!: Renamed main build job
    Renamed main build job from `build-base` to `base`
    BREAKING CHANGE: The `build-base` is now named `base`
    123

[mainrs]

This could be taken further by introducing some kind of template where a user can define their own template and formatting (commits.template):

{type}{if has_scope: ({scope})}{if is_breaking: !}: {short_msg}
{long_msg}
{if is_breaking: BREAKING CHANGES: {breaking_changes}}
{if are_affected: issues_affected}

Just an idea :)

[tbarusseau]

Are you alright with adding structopt for command-line arguments parsing?

[mainrs]

I've worked with both structopt and clap. Since structopt does rely on clap anyway and has been merged into the 3.0-alpha I'd rather use that version of clap.

[mainrs]

I am working on #12, so this could be solved with it. Not sure if I want to add a flag for it or just provide an alternative template inside the repo that people can use, as my main goal is to follow the conventional commits specification.

[tbarusseau]

While it makes sense for the spec to separate the title, body, and footer, on shorter commit messages it's a pity to have 2 newlines for 3 lines of content. I agree that it's important to follow a specification for the commits, but if only the commits were pretty to look at as well!

[mainrs]

So I have thinking about this for a while and I will probably include a compact version of the current template without the new lines. However, the help screen will have a note that it is not compliant with the specification.

[tbarusseau]

That sounds great!