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/diamond.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="diamond">
+  <path d="M7.03715 1.20147L2.12542 6.7C2.04962 6.78393 2.00568 6.89005 2.00051 7C1.99535 7.10994 2.02925 7.21013 2.09689 7.3L7.0065 13.7601C7.06233 13.8343 7.13629 13.8947 7.22216 13.9365C7.30803 13.9782 7.40331 14 7.5 14C7.59669 14 7.69197 13.9782 7.77784 13.9365C7.86371 13.8947 7.93766 13.8343 7.9935 13.7601L12.9031 7.3C12.9707 7.21013 13.0047 7.10994 12.9995 7C12.9943 6.89005 12.9504 6.78393 12.8746 6.7L7.96285 1.20147C7.90591 1.13833 7.83501 1.08761 7.75508 1.05282C7.67514 1.01802 7.5881 1 7.5 1C7.4119 1 7.32486 1.01802 7.24492 1.05282C7.16499 1.08761 7.09409 1.13833 7.03715 1.20147Z"/>
+</svg>