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/town-hall.svg

@@ -0,0 +1,4 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<svg version="1.1" id="town-hall" xmlns="http://www.w3.org/2000/svg" width="15" height="15" viewBox="0 0 15 15">
+  <path d="M13,4H9l0-3L7.5,0L6,1v3H2L1,5v1h13V5L13,4z M7.5,1.5c0.4,0,0.7,0.3,0.7,0.8S7.9,3,7.5,3S6.7,2.7,6.7,2.2&#xA;&#x9;C6.7,1.8,7.1,1.5,7.5,1.5z M13,7H2v4l-1,1.5V14h13v-1.5L13,11V7z M5,12.5H4V8h1V12.5z M8,12.5H7V8h1V12.5z M11,12.5h-1V8h1V12.5z"/>
+</svg>