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/en.yaml

@@ -1,9 +1,14 @@
+calendar_ics: "iCal download"
+calendar_google: "Google calendar"
+calendar_meeting_point: "Hackertours Desk"
 logo_alt: "Hamburg Hackertours – home page"
 map_39c3_title: "Map of the 39C3 tours with routes from the CCH (uMap)"
 schedule_day: "Day {{ .Day }}"
 schedule_pick_day: "Choose a day"
 schedule_soldout: "fully booked"
 skip_to_content: "Skip to content"
+tour_map_label: "Map of the tour locations"
+tour_map_osm: "on OpenStreetMap"
 gallery_enlarge: "enlarge"
 gallery_dialog: "Image viewer"
 gallery_close: "Close"