Renovate CLI switch parsing

[thornjad]

This commit makes a handful of closely-related changes, all aimed at refactoring bin/http-server for better maintainability.

• Switched from deprecated optimist to the smaller minimist for CLI parsing
• Used aliases to link together switches with both a - and -- option, thereby removing the need for patterns like argv.g || argv.gzip
• Set defaults on almost all switches. This can make debugging easier and makes default values more clear
• Reformatted the help dialog
• Clarified the help dialog to take a sidestep around Make Boolean command line switches case insensitive #450. As noted in How to disable directory listings? #200 (comment), False is a string, so it should not work on a boolean switch. Instead, this new help dialog encourages using the --no prefix. For example, -i enables autoIndex, and --no-i disables it. This is already possible, so it's not actually an interface change
• As far as I can tell, this PR introduces no user-facing changes except for the help dialog

[BigBlueHat]

Thanks for tackling this! We do need to get off optimist, and minimist seems sufficient with the least amount of code restructuring.

I left a few inline comments which would hopefully help make the usage code a bit clearer.

Appreciate the contribution!
🎩

[thornjad]

I'm currently working my way through the pile of PRs, and I have to say I like #131 better than this approach. @BigBlueHat @indexzero what do you think about this minimist PR vs nconf? I definitely like the idea of a .httpserverrc.

[thornjad]

I am officially laying this PR down in favor of nconf in #131, it's very well done over there.