Refactor CLI to use "commands"

First, this project is great. Keep up the good work.

This is a proposal for a redesign of the CLI interface. I’d be happy to put in a PR for if it seems like a good thing to do.

A Proposal

Redesign the CLI interface to use “commands” instead of options.

$ lume --help

  🔥lume v0.14.0
  A static site generator for Deno

  Docs:

    https://lumeland.github.io

  Usage:

    lume [OPTIONS] COMMAND

  Options:

    -h, --help     - Show this help.
    -V, --version  - Show the version number for this program.

  Commands:

    build [config]  - build the site
    init            - create a _config.js file for a new site
    serve           - Build the site and start a web server that refreshes automatically for every change
    upgrade         - Upgrade local lume install to the latest version
    update          - Update the lume version imported in _config.js to the latest

Each command would have its own --help output as well, specifying the relevant options for that command

---

If this looks like a good direction for lume I can get a PR ready sometime this week

[JordanShurmer]

Awesome. Thanks for the quick feedback. Good to see work already being done on this front @oscarotero.

I will check out that branch and contribute where I can.

[JordanShurmer]

Closed by #34