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/mountain_asterisk.svg

@@ -0,0 +1,4 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<svg viewBox="0 0 15 15" version="1.1" xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink">
+  <path d="M5 1L7 4L10.5 2.5L14.97 13L0 13L5 1ZM8.25 5L6.75 5L6.75 7.2L4.84 6.1L4.09 7.4L6 8.5L4.09 9.6L4.84 10.9L6.75 9.8L6.75 12L8.25 12L8.25 9.8L10.16 10.9L10.91 9.6L9 8.5L10.91 7.4L10.16 6.1L8.25 7.2L8.25 5Z"/>
+</svg>