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/baseball.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="baseball">
+  <path d="m9.00003 3.5c0 .8284-.6716 1.5-1.5 1.5s-1.5-.6716-1.5-1.5.6716-1.5 1.5-1.5 1.5.6716 1.5 1.5zm-3-3.22c0-.1546-.1254-.28-.28-.28-.0979.0262-.1852.0821-.25.16l-2.47 4.43c-.0059.0431-.0059.0869 0 .13 0 .1546.1254.28.28.28.1015-.0243.1926-.0803.26-.16l2.46-4.43c.006-.0431.006-.0869 0-.13zm5.89997 13.92-2.89997-7.81c-.0474-.2273-.2478-.3901-.48-.39h-5c-.2761 0-.5.2239-.5.5s.2239.5.5.5h2.48l1.45 2.51-4.27 4.61c-.1141.0932-.1802.2327-.18.38 0 .2761.2239.5.5.5.1224-.0006.2401-.047.33-.13l4.45-4.15 2.75997 4c.0895.1592.2574.2584.44.26.2796.0002.5092-.2207.52-.5-.0042-.1013-.039-.199-.1-.28z"/>
+</svg>