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/tower.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="M6 5.5L9 5.5C9 5.5 9 13.5 9 14C9 15 6 15 6 14C6 13.5 6 5.5 6 5.5zM10.5 2L10 4L8 4L8 2L10.5 2zM7 2L7 4L5 4L4.5 2L7 2zM9.5 0L5.5 0L5 1L3 1L4 5L11 5L12 1L10 1L9.5 0z"/>
+</svg>