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/tunnel.svg

@@ -0,0 +1,4 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<svg viewBox="0 0 15 15" version="1.1" xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink">
+  <path d="M4.5 3L10.5 3C12.99 3 15 5.01 15 7.5L15 11.5C15 11.78 14.78 12 14.5 12L0.5 12C0.22 12 0 11.78 0 11.5L0 7.5C0 5.01 2.01 3 4.5 3ZM4.5 4C2.57 4 1 5.57 1 7.5L1 11L8 11L8 7.5C8 5.57 6.43 4 4.5 4ZM4.5 5C5.88 5 7 6.12 7 7.5L7 11L2 11L2 7.5C2 6.12 3.12 5 4.5 5Z"/>
+</svg>