New group buttons, classes, sub navigation and other stuff

First update for Proton Design system, here is the changelog:

New

• added sub navigation (buttons + IntersectionObserver + scrollIntoView stuff)
• refactored group buttons
• added classes is-hover and is-active for buttons
• added exception for main content without toolbar (main-area--noToolbar)
• styled buttons in left toolbar (PM, PVPN, burger, etc.)

Fixed

• renamed svg sprite
• updated modal code
• fixed print version
• reordered import to have helper working properly on Hx stuff
• bugfixes

Misc

• added changelog
• semver project