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/lift-gate.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="lift-gate">
+  <path d="M1 4a2 2 0 1 1 4 0v8a1 1 0 0 1-1 1H2a1 1 0 0 1-1-1V4Zm3 0a1 1 0 1 0-2 0 1 1 0 0 0 2 0Zm4.5 2L7 3H6v3h2.5ZM10 6h1.5L10 3H8.5L10 6Zm3.25 0H13l-1.5-3h1.75a.75.75 0 0 1 .75.75v1.5a.75.75 0 0 1-.75.75Z"/>
+</svg>