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/fontawesome/brands/renren.svg

@@ -0,0 +1 @@
+<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 512 512"><!--! Font Awesome Free 7.3.1 by @fontawesome - https://fontawesome.com License - https://fontawesome.com/license/free (Icons: CC BY 4.0, Fonts: SIL OFL 1.1, Code: MIT License) Copyright 2026 Fonticons, Inc. --><path fill="currentColor" d="M214 169.1C214 279.5 153 374.5 66.4 416.5 30 373.2 8 317.7 8 256.6 8 133.9 97.1 32.2 214 12.5l0 156.6zM255 504c-42.9 0-83.3-11-118.5-30.4 57.2-36.1 103.4-90.7 118.5-154.6 15.5 63.9 61.7 118.5 118.8 154.7-35.1 19.3-75.5 30.3-118.8 30.3zm190.6-87.5C359 374.5 298 279.6 298 169.1l0-156.6c116.9 19.7 206 121.4 206 244.1 0 61.1-22 116.6-58.4 159.9z"/></svg>