40C3: tours, schedule data, tour map and calendar entries

- tour-map shortcode: Leaflet map of the tour locations with routes from the
  Congress, from the map/tours sections of data/schedule/<event>.yaml; Leaflet
  and the OSMIC, Maki and Temaki icon sets vendored; 39C3 uMap data converted.
- calendar shortcode: per tour date, a pill with an .ics download (iCalendar)
  and a Google Calendar link; Font Awesome Free vendored, fa-icon partial.
- README sections for the calendar and tour map shortcodes and the map data.

assets/vendor/icons/maki/bus.svg

@@ -0,0 +1,4 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<svg width="15" height="15" viewBox="0 0 15 15" xmlns="http://www.w3.org/2000/svg" id="bus">
+  <path d="M2 3C2 1.9 2.9 1 4 1H11C12.1 1 13 1.9 13 3V11C13 12 12 12 12 12V13C12 13.55 11.55 14 11 14C10.45 14 10 13.55 10 13V12H5V13C5 13.55 4.55 14 4 14C3.45 14 3 13.55 3 13V12C2 12 2 11 2 11V3ZM3.5 4C3.22 4 3 4.22 3 4.5V7.5C3 7.78 3.22 8 3.5 8H11.5C11.78 8 12 7.78 12 7.5V4.5C12 4.22 11.78 4 11.5 4H3.5ZM4 9C3.45 9 3 9.45 3 10C3 10.55 3.45 11 4 11C4.55 11 5 10.55 5 10C5 9.45 4.55 9 4 9ZM11 9C10.45 9 10 9.45 10 10C10 10.55 10.45 11 11 11C11.55 11 12 10.55 12 10C12 9.45 11.55 9 11 9ZM4 2.5C4 2.78 4.22 3 4.5 3H10.5C10.78 3 11 2.78 11 2.5C11 2.22 10.78 2 10.5 2H4.5C4.22 2 4 2.22 4 2.5Z"/>
+</svg>