Push docs forward a bit

 - use different template for homepage and content pages
 - make a distinctive header image
 - rename lib to src and move coding and vendor under it
Rough in bottom nav on content pages
Tweak layout and nav

 - implement width on page content
 - start adding breadcrumbs
 - move bottom homepage link from left to right side (less conflict with
   browser's link URL indicator, and eye flows top left to low right so
   lower right is "the end of the line," a natural place to look to go
   back home.)