Update design

[ericwbailey]

This PR:

• Updates the design
• Adds a logo
• Uses a mobile-first design for consumption on smartphone
• Adds dark mode support
• Adds basic social media sharing support
• Adds an .editorconfig for helping to enforce code consistency
• Adds IDs to headings, for easier sharing
• Cleans up the markup some
• Standardizes content to an 80 character line width
• Breaks some paragraphs up for easier consumption, see Content structure suggestion #111
• Adds myself as an undersigned

[ericwbailey]

@karlgroves Merge conflicts should be set. I have signatures and further reading updated as of d054bf3's timestamp, but have not granularly reviewed content.