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.

content/de/39c3/_index.md

@@ -2,9 +2,6 @@
 title: 39C3 Touren
 weight: 10
 layout: list-bytitle
-menus:
-  main:
-    name: Touren
 params:
   showPostDate: false
 cascade: