Offer more fonts to use in block formatting

[Dan-Peck]

Offering more fonts could allow for more custom tailoring of Screens.

Possibilities:

• Utilize Google Fonts API to query for its huge list of available fonts, perhaps even sorting by popularity ( https://developers.google.com/fonts/docs/developer_api )
• Divvy up into categories:
  • Serif
  • Sans Serif
  • Display
  • Handwritten
  • Monospace
• Provide a widget that allows for searching by text in addition to clicking on a selection
• Provide a "Sample" of text that shows in the selected font
• Possibly format the selector similarly to the Icon selector widget, but for fonts?