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/racetrack_oval.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="M3.62 8.56C2.83 9.34 2.83 10.61 3.62 11.39C4.4 12.17 5.66 12.17 6.44 11.39L11.39 6.44C12.17 5.66 12.17 4.39 11.39 3.61C10.61 2.83 9.35 2.83 8.57 3.61L3.62 8.56ZM1.49 6.44L6.44 1.49C8.4 -0.46 11.56 -0.46 13.52 1.49C15.47 3.44 15.47 6.61 13.52 8.56L8.57 13.51C6.61 15.46 3.45 15.46 1.49 13.51C-0.46 11.56 -0.46 8.39 1.49 6.44ZM2.91 7.85L7.86 2.9C9.03 1.73 10.93 1.73 12.1 2.9C13.27 4.08 13.27 5.97 12.1 7.15L7.15 12.1C5.98 13.27 4.08 13.27 2.91 12.1C1.74 10.92 1.74 9.03 2.91 7.85ZM2.2 7.15C0.64 8.71 0.64 11.24 2.2 12.8C3.76 14.37 6.3 14.37 7.86 12.8L12.81 7.85C14.37 6.29 14.37 3.76 12.81 2.2C11.25 0.63 8.71 0.63 7.15 2.2L2.2 7.15Z"/>
+</svg>