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/plant.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="M9.98 0C9.98 2 9.65 3.5 9 4.5C8.67 5.01 8.34 5.38 8 5.63L8 7C8.33 6.31 8.82 5.69 9.44 5.22L11 4C11 6.22 10.04 8.34 8.37 9.8L8 10.12L8 11.66C8.8 10.09 10.11 8.83 11.73 8.11L12 8L12 9C12 11.42 10.28 13.44 8 13.9L8 15L7 15L7 13.9C4.79 13.45 3.11 11.54 3 9.23L3 9L3 8L3.27 8.11C4.89 8.83 6.2 10.09 7 11.66L7 10.13L6.63 9.8C5.03 8.4 4.08 6.41 4.01 4.29L4 4L5.56 5.22C6.18 5.69 6.67 6.31 7 7L7 6L7 6L7 5.98L7 5.64C6.66 5.39 6.33 5.01 6 4.5C5.35 3.5 5.02 2 5.02 0C6.07 0.63 6.93 1.7 7.43 3L7.57 3C8.07 1.7 8.93 0.63 9.98 0Z"/>
+</svg>