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/rocket.svg

@@ -0,0 +1,4 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<svg height="15" viewBox="0 0 15 15" width="15" xmlns="http://www.w3.org/2000/svg" id="rocket">
+  <path d="m11.5547 2c-2.14407 0-5.02107 1.471-6.95307 4h-1.6016c-1.1573 0-1.8206.8638-2.277302 1.7773l-.6114 1.2227h1.443402 1.4453l1.5 1.5 1.5 1.5v1.4453 1.4434l1.2227-.6113c.9135-.4568 1.7773-1.1201 1.7773-2.2774v-1.6016c2.52897-1.932 3.99997-4.809 3.99997-6.9531v-1.4453zm-2.55467 3c.5523 0 .99997.4477.99997 1s-.44767 1-.99997 1-1-.4477-1-1 .4477-1 1-1zm-6.5 6-.5.5c-.7222.7222-1 2.5-1 2.5s1.698-.198 2.5-1l.5-.5z"/>
+</svg>