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/maki/restaurant-pizza.svg

@@ -0,0 +1,4 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<svg width="15" height="15" viewBox="0 0 15 15" xmlns="http://www.w3.org/2000/svg" id="restaurant-pizza">
+  <path d="M1.393 7.931.025 7.315A14.05 14.05 0 0 1 7.764-.001l.027.07.511 1.331-.003.001a12.613 12.613 0 0 0-6.906 6.53Zm10.963 4.96L2.42 8.414a11.604 11.604 0 0 1 6.354-6.009l.003-.001.817 2.122c-.028-.002-.052-.016-.081-.016a1.062 1.062 0 1 0 .764 1.793l2.413 6.273a.249.249 0 0 1-.334.316ZM7.426 7.52a.925.925 0 1 0-1.849 0 .925.925 0 0 0 1.849 0Zm3.017 2.03a.925.925 0 1 0-.07.353.924.924 0 0 0 .07-.354Z"/>
+</svg>