Normalize CLI options, switch to yargs

[FloEdelmann]

Use the same command line parameters for similar functions (e.g. always --plugin / -p for fixture import, export, export test, etc.).

Also use minimist for main.js to set the port and dev server.

And in the same PR, we could switch from the colors devDependency to chalk as it's more versatile and less confusing (colors vs. color vs. color-names). (done separately)

[FloEdelmann]

Also bring all CLI tools' help messages into line. If they output usable plugin keys, those should not be hardcoded, but taken from plugins.json.

[FloEdelmann]

Also update references to the CLI tool usage in the docs and in GitHub tests.

[FloEdelmann]

A potentially useful tool: https://github.com/tj/commander.js

[Swiftb0y]

I am feeling quite limited by minimist. It's also not been maintained by quite some time now. Does anything speak against phasing out minimist in favor of commander.js or yargs (slightly more features)?

[fxedel]

I have no problem with replacing the minimist library, we should only be consistent and use the new dependency in every CLI script then. In fact, tackling this issue is a good occasion to replace the old library 👍