Issue #1946216 by rupl, iwuv: add Modernizr hook
Issue #1867650 by Drave Robber: fix Add selector in theme CSS instructions
Issue #1923732 by Drave Robber: zero fonts display bug
Issue #1923604 by chriz001: fix fonts.com import
Issue #1976444 by sreynen: make no providers enabled message clearer.
Issue #1956678 by sreynen: Fix font reference field for enable fonts with no CSS selector set
Issue #1850206 by sreynen: move more fields from schema to field API
Issue #1850206 by sreynen: update code to work with D8 core updates
Issue #1850206 by sreynen: add more fields
Issue #1929858 by sreynen: very basic font view