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/circle-stroked.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="circle-stroked">
+  <path d="M7.5 12.3C4.84898 12.3 2.7 10.151 2.7 7.5C2.7 4.84898 4.84898 2.7 7.5 2.7C10.151 2.7 12.3 4.84898 12.3 7.5C12.3 10.151 10.151 12.3 7.5 12.3ZM7.5 14C11.0899 14 14 11.0899 14 7.5C14 3.9101 11.0899 1 7.5 1C3.9101 1 1 3.9101 1 7.5C1 11.0899 3.9101 14 7.5 14Z"/>
+</svg>