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/bulletin_board.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="M0.5 2L14.5 2C14.78 2 15 2.22 15 2.5L15 12.5C15 12.78 14.78 13 14.5 13L0.5 13C0.22 13 0 12.78 0 12.5L0 2.5C0 2.22 0.22 2 0.5 2ZM3.3 2.75L1.75 8.55L6.1 9.71L7.65 3.91L3.3 2.75ZM7.5 6.41L9.05 12.21L10.02 11.95L9.63 10.5L10.6 10.24L10.98 11.69L13.4 11.05L12.23 6.69L11.85 5.25L7.5 6.41Z"/>
+</svg>