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/observation-tower.svg

@@ -0,0 +1,4 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<svg xmlns="http://www.w3.org/2000/svg" width="15" height="15" viewBox="0 0 15 15" id="observation-tower">
+  <path d="M12 12.5H11.5L10 9V7C10.9951 7 10.9951 6.25 10.9951 6.25L11.5 3C11.5 3 11.5 2.5 11 2.5H10C10 2.5 10 2 9.5 2H8.5V1.5C8.5 1.5 8.5 0.5 7.5 0.5C6.5 0.5 6.5 1.5 6.5 1.5V2H5.5C5 2 5 2.5 5 2.5H4C3.5 2.5 3.5 3 3.5 3L4.0049 6.25C4.0049 6.25 4.0049 7 5 7V9L3.5 12.5H3C3 12.5 2 12.5 2 13.25C2 14 3 14 3 14H12C12 14 13 14 13 13.25C13 12.5 12 12.5 12 12.5ZM10.25 3.5L10 5H5L4.75 3.4971L10.25 3.5ZM8.5 7V8H6.5V7H8.5ZM6.5006 9.4971H8.4994L9.5 12.5H5.5L6.5006 9.4971Z"/>
+</svg>