UX & API

[alekseykulikov]

Tasks:

• [x] rename to unslow
• [x] rebuild cli to pass [path] as the only argument
• [x] resolve path/folder as an array of names + remove chromeExtensions + firefoxExtensions from settings.js
• [x] fix typescript errors
• [x] better defaults, clean-up code, improve interactive display
• [x] fix --runs=p & review cli params
• [x] speed up: try --headless for default