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/skateboard.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="skateboard">
+  <path d="M1.25 5.25V5H2.75V5.25C2.75 5.94036 3.30964 6.5 4 6.5H11C11.6904 6.5 12.25 5.94036 12.25 5.25V5H13.75V5.25C13.75 6.76878 12.5188 8 11 8H4C2.48122 8 1.25 6.76878 1.25 5.25ZM5 10C5 10.5523 4.55228 11 4 11 3.44772 11 3 10.5523 3 10 3 9.44772 3.44772 9 4 9 4.55228 9 5 9.44772 5 10ZM12 10C12 10.5523 11.5523 11 11 11 10.4477 11 10 10.5523 10 10 10 9.44772 10.4477 9 11 9 11.5523 9 12 9.44772 12 10Z"/>
+</svg>