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/residential-community.svg

@@ -0,0 +1,4 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<svg height="15" viewBox="0 0 15 15" width="15" xmlns="http://www.w3.org/2000/svg" id="residential-community">
+  <path d="m11.8 12.5v-2.5c.7-.1 1.2-.7 1.2-1.5s-.7-1.5-1.5-1.5-1.5.7-1.5 1.5c0 .7.5 1.4 1.2 1.5v2.5h-4.2v-11.5h-5v11.5h-1v.5h13v-.5zm-5.8-2.5h-3v-1h3zm0-2h-3v-1h3zm0-2h-3v-1h3zm0-2h-3v-1h3z"/>
+</svg>