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/row_houses.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="M10 14L5 14L5 11L3 11L3 14L1 14L1 5.5L14 5.5L14 14L12 14L12 11L10 11L10 14ZM7.25 13L7.75 13L7.75 6.5L7.25 6.5L7.25 13ZM3 7L3 9L5 9L5 7L3 7ZM12 7L10 7L10 9L12 9L12 7ZM11 0.5L14.5 4L14.5 5L0.5 5L0.5 4L4 0.5L7.5 4L11 0.5Z"/>
+</svg>