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/snowmobile.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="snowmobile">
+  <path d="M15 10a1 1 0 0 1-1 1H9.414a1 1 0 0 1-.707-.293L7.146 9.146A.499.499 0 0 0 6.793 9H3.334a1 1 0 0 1-.601-.2L1.386 7.788A1.013 1.013 0 0 1 1 7a.995.995 0 0 1 .472-.844L5 4l1.038-1.692A.5.5 0 0 1 7 2.5V6l1 1h1l5.412-.992a.5.5 0 0 1 .355.915L13 8l1.631 1.224A.99.99 0 0 1 15 10Zm-9.5 0H3.225c-.504 0-.999-.127-1.44-.368L.74 9.062a.5.5 0 0 0-.48.877l1.269.693c.441.242.937.368 1.44.368H5.5a.5.5 0 0 0 0-1Z"/>
+</svg>