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/x_oblique.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="M7.5 6.36L13.53 3.12C14.01 2.86 14.62 3.04 14.88 3.53C15.14 4.01 14.96 4.62 14.47 4.88L9.61 7.5L14.47 10.12C14.96 10.38 15.14 10.99 14.88 11.47C14.62 11.96 14.01 12.14 13.53 11.88L7.5 8.64L1.47 11.88C0.99 12.14 0.38 11.96 0.12 11.47C-0.14 10.99 0.04 10.38 0.53 10.12L5.39 7.5L0.53 4.88C0.04 4.62 -0.14 4.01 0.12 3.53C0.38 3.04 0.99 2.86 1.47 3.12L7.5 6.36Z"/>
+</svg>