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/temaki/railing.svg

@@ -0,0 +1,4 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<svg version="1.1" xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink" x="0" y="0" viewBox="0 0 15 15">
+  <path d="M13.5 12H13V4.5a0.5 0.5 0 0 0 -1 0V5H3V4.5a0.5 0.5 0 0 0 -1 0V12H1.5a0.5 0.5 0 0 0 0 1h2a0.5 0.5 0 0 0 0 -1H3V11h9v1h-0.5a0.5 0.5 0 0 0 0 1h2a0.5 0.5 0 0 0 0 -1ZM3 10V6H4v4Zm2 0V6H6v4Zm2 0V6H8v4Zm2 0V6h1v4Zm3 0H11V6h1Z"/>
+</svg>