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/planes.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="M4 0C4.67 0 5 0.67 5 2L5 2.5L8 5L8 6L5 5L5 7L6 8L6 9L4 8L2 9L2 8L3 7L3 5L0 6L0 5L3 2.5L3 2C3 0.67 3.33 0 4 0ZM11 6C11.67 6 12 6.67 12 8L12 8.5L15 11L15 12L12 11L12 13L13 14L13 15L11 14L9 15L9 14L10 13L10 11L7 12L7 11L10 8.5L10 8C10 6.67 10.33 6 11 6Z"/>
+</svg>