Add missing mode icons

[flibbertigibbet]

New fontello font icons are missing icons for several transportation modes.

Needed are:

• bus
  • subway
  • car (should not be visible, but good to have to debug if we ever got car directions)
  • rail (not the same as 'train', which we have)
  • tram
  • ferry

[flibbertigibbet]

Also missing some directions icons:

• continue (was using an up-pointing arrow)
• circle clockwise or counterclockwise (was using a repeat icon)
• elevator (was using a cloud-upload icon, hopefully we can find something more appropriate)
• default icon (was the glyphicon remove-circle, not sure what that looks like)