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.

i18n/de.yaml

@@ -1,9 +1,14 @@
+calendar_meeting_point: "Hackertours-Desk"
+calendar_ics: "iCal Download"
+calendar_google: "Google Calendar"
 logo_alt: "Hamburg Hackertours – Startseite"
 map_39c3_title: "Karte der 39C3-Touren mit Wegen vom CCH (uMap)"
 schedule_day: "Tag {{ .Day }}"
 schedule_pick_day: "Tag auswählen"
 schedule_soldout: "ausgebucht"
 skip_to_content: "Zum Inhalt springen"
+tour_map_label: "Karte der Tourorte"
+tour_map_osm: "auf OpenStreetMap"
 gallery_enlarge: "Großansicht"
 gallery_dialog: "Bildansicht"
 gallery_close: "Schließen"