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/temaki/real_estate_agency.svg

@@ -0,0 +1,4 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<svg version="1.1" xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink" x="0" y="0" viewBox="0 0 15 15">
+  <path d="M14 13L14 4L4 4L4 13zM9 5L13.5 9L12 9L12 12L10 12L10 10L8 10L8 12L6 12L6 9L4.5 9L9 5zM3 2C3 2 3 1 3 1C3 0.5 1 0.5 1 1C1 1 1 15 1 15L3 15L3 3C3 3 14 3 14 3C14.5 3 14.5 2 14 2C14 2 3 2 3 2z"/>
+</svg>