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/tree_and_bench.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="M4 10.94L4 14L3 14L3 10.95C1.93 10.73 1.12 9.77 1.12 8.63C1.12 8.5 1.13 8.37 1.15 8.24C1.97 3.41 2.77 1 3.56 1C4.34 1 5.11 3.41 5.86 8.23L5.86 8.23C6.05 9.49 5.23 10.68 4 10.94ZM6 11L14 11L14 14L13 14L13 12L7 12L7 14L6 14L6 11ZM7 8L13 8L13 10.5L7 10.5L7 8Z"/>
+</svg>