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/triangle-stroked.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="triangle-stroked">
+  <path d="m7.52427.500405c-.2814-.0091-.5456.1419-.6907.3948l-5.5 9.869195c-.3118.5434.0614 1.2355.6664 1.2356h11.00003c.605-.0001.9782-.6922.6664-1.2355l-5.50003-9.869195c-.1362-.2374-.378-.3861-.6421-.3949zm-.0243 2.398895 4.12673 7.4704h-8.25343z"/>
+</svg>