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/cross.svg

@@ -0,0 +1,4 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<svg width="15" height="15" viewBox="0 0 15 15" xmlns="http://www.w3.org/2000/svg" id="cross">
+  <path d="M3.64 2.27L7.5 6.13L11.34 2.29C11.5114 2.1076 11.7497 2.0029 12 2C12.5523 2 13 2.4477 13 3C13.0047 3.2478 12.907 3.4866 12.73 3.66L8.84 7.5L12.73 11.39C12.8948 11.5512 12.9915 11.7696 13 12C13 12.5523 12.5523 13 12 13C11.7423 13.0107 11.492 12.9127 11.31 12.73L7.5 8.87L3.65 12.72C3.4793 12.8963 3.2453 12.9971 3 13C2.4477 13 2 12.5523 2 12C1.9953 11.7522 2.093 11.5134 2.27 11.34L6.16 7.5L2.27 3.61C2.1052 3.4488 2.0085 3.2304 2 3C2 2.4477 2.4477 2 3 2C3.2404 2.0029 3.4701 2.0998 3.64 2.27Z"/>
+</svg>