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/pickleball.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="M2 12C2.25 12.75 2.25 12.75 3 13L6 10C6.5 9.5 7.25 9.8 8 10C9 10.35 9.75 9.75 10.5 9L13 6.5C13.75 5.75 13.75 4.75 13 4L11 2C10.25 1.25 9.25 1.25 8.5 2L6 4.5C5.25 5.25 4.65 6 5 7C5.2 7.75 5.5 8.5 5 9ZM10 11A1.5 1.5 0 0 0 10 14A1.5 1.5 0 0 0 10 11Z"/>
+</svg>