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/slide.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="M1 11L4 11L4 9L1 9L1 11ZM1 12L1 14L0 14L0 5.62C-0.31 5.34 -0.5 4.94 -0.5 4.5C-0.5 4.06 -0.31 3.66 0 3.38L0 1.5C0 1.22 0.22 1 0.5 1C0.78 1 1 1.22 1 1.5L1 3L4 3L4 1.5C4 1.22 4.22 1 4.5 1C4.78 1 5 1.22 5 1.5L5 3.05C5.59 3.17 6.13 3.51 6.5 4L11.75 11L13.5 11C14.33 11 15 11.67 15 12.5C15 13.33 14.33 14 13.5 14L11.5 14C10.71 14 9.97 13.63 9.5 13L5 7L5 14L4 14L4 12L1 12L1 12ZM1 8L4 8L4 6L1 6L1 8L1 8Z"/>
+</svg>