Better citation styling

Signed-off-by: Dan Scott <dan@coffeecode.net>
Add LU logo

Signed-off-by: Dan Scott <dan@coffeecode.net>
Include some code / book example callouts

Signed-off-by: Dan Scott <dan@coffeecode.net>
Clean up turtle code display

Signed-off-by: Dan Scott <dan@coffeecode.net>