Hamburger Icon, small enhancements

[carstene1ns]

• Responsive menu
• css/js is combined, compressed and hashed now
• scss is split in import modules
• doc update
• added typografy enhancements

[carstene1ns]

https://deploy-preview-82--easyrpg.netlify.app/ <- be sure to scale screen under 700px wide.

[carstene1ns]

Good idea, will add later.

Apropos, we could use something different than hamburger, e.g.

Initially thought about animated trisquel, but some might not see this as menu icon then...

[carstene1ns]

Updated description. This one is ready.