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/elevator.svg

@@ -0,0 +1,4 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<svg xmlns="http://www.w3.org/2000/svg" id="elevator" width="15" height="15" viewBox="0 0 15 15">
+  <path d="M11,1H4A1,1,0,0,0,3,2V13a1,1,0,0,0,1,1h7a1,1,0,0,0,1-1V2A1,1,0,0,0,11,1ZM7.5,12.5l-2-4h4Zm-2-6,2-4,2,4Z"/>
+</svg>