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/hotpot.svg

@@ -0,0 +1,4 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 100 100">
+  <path d="M19 48L79 48C83.4 48 82 50 83 50C85 50 84 48.2 85 48L95 46C97.05 45.56 98 47.97 95.8 48.56L85.82 50.53C84.93 50.73 84.73 51.36 84.72 51.87C84 89 14 89 13.22 51.87C13.21 51.35 13.02 50.72 12.12 50.53L2.14 48.55C0.5 48.18 1.1 45.58 2.91 45.99L13 48C14 48.2 13 50 15 50C16 50 14.6 48 19 48ZM27 38C28 40 32 38 31 36C27 28 37 24 31 12C30 10 26 12 27 14C31 22 21 26 27 38M47 38C48 40 52 38 51 36C47 28 57 24 51 12C50 10 46 12 47 14C51 22 41 26 47 38M67 38C68 40 72 38 71 36C67 28 77 24 71 12C70 10 66 12 67 14C71 22 61 26 67 38"/>
+</svg>