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/parking-paid.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="parking-paid">
+  <path d="M1 13V2h4.5a3.5 3.5 0 0 1 3.21 2.103 3.36 3.36 0 0 0-.504.676c-.23.41-.232.837-.174 1.154l.3 1.625A3.495 3.495 0 0 1 5.5 9H3v4H1Zm4.5-6a1.5 1.5 0 1 0 0-3H3v3h2.5Zm3.516-1.248a.716.716 0 0 1 .062-.484C9.315 4.848 9.978 4 11.5 4c1.521 0 2.185.847 2.421 1.268a.716.716 0 0 1 .064.484L13.019 11H12v2h-1v-2H9.981l-.965-5.248ZM12.75 7 13 5.655C12.83 5.409 12.42 5 11.5 5s-1.33.41-1.5.655L10.25 7h2.5Z"/>
+</svg>