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/triangle.svg

@@ -0,0 +1,4 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<svg height="15" viewBox="0 0 15 15" width="15" xmlns="http://www.w3.org/2000/svg" id="triangle">
+  <path d="m7.5385 1c-.2948 0-.4883.1772-.6154.3846l-5.8462 9.5385c-.0769.0769-.0769.2307-.0769.3846 0 .5385.3846.6923.6923.6923h11.6154c.3846 0 .6923-.1538.6923-.6923 0-.1538 0-.2308-.0769-.3846l-5.7693-9.5385c-.1258-.2081-.3656-.3846-.6153-.3846z"/>
+</svg>