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/mountain_cross.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="M5 1L7 4L10.5 2.5L14.97 13L0 13L5 1ZM8 5L7 5C6.75 5 6.55 5.18 6.51 5.41L6.5 5.5L6.5 7.5L4.5 7.5C4.25 7.5 4.05 7.68 4.01 7.91L4 8L4 9C4 9.25 4.18 9.45 4.41 9.49L4.5 9.5L6.5 9.5L6.5 11.5C6.5 11.75 6.68 11.95 6.91 11.99L7 12L8 12C8.25 12 8.45 11.82 8.49 11.59L8.5 11.5L8.5 9.5L10.5 9.5C10.75 9.5 10.95 9.32 10.99 9.09L11 9L11 8C11 7.75 10.82 7.55 10.59 7.51L10.5 7.5L8.5 7.5L8.5 5.5C8.5 5.25 8.32 5.05 8.09 5.01L8 5Z"/>
+</svg>