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/historic.svg

@@ -0,0 +1,4 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<svg version="1.1" id="historic" xmlns="http://www.w3.org/2000/svg" width="15" height="15" viewBox="0 0 15 15">
+  <path d="m7.5 1c-1 0-1 1-2 1h-3.5c-.54467 0-1 .45533-1 1v7c0 .5447.45533 1 1 1h5v2.5s0 .5.5.5.5-.5.5-.5v-2.5h5c.5447 0 1-.4553 1-1v-7c0-.54467-.4553-1-1-1h-3.5c-1 0-1-1-2-1zm-4.5 4v-1h9v1zm0 1h4v1h-4zm0 2h7v1h-7z"/>
+</svg>