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.

layouts/_partials/ics-line.html

@@ -0,0 +1,22 @@
+{{- /*
+One iCalendar (RFC 5545) content line: "NAME:value" plus CRLF, folded so that no line is
+longer than 75 bytes (continuation lines start with a space). Params: name, value, text
+(true to escape the value as TEXT: backslash, semicolon, comma and newlines).
+*/ -}}
+{{- $value := .value | default "" -}}
+{{- if .text -}}
+  {{- $value = $value | replaceRE `\\` `\\` | replaceRE `;` `\;` | replaceRE `,` `\,` | replaceRE `\r?\n` `\n` -}}
+{{- end -}}
+{{- $out := "" -}}
+{{- $line := "" -}}
+{{- $bytes := 0 -}}
+{{- range split (printf "%s:%s" .name $value) "" -}}
+  {{- if gt (add $bytes (len .)) 75 -}}
+    {{- $out = printf "%s%s\r\n " $out $line -}}
+    {{- $line = "" -}}
+    {{- $bytes = 1 -}}
+  {{- end -}}
+  {{- $line = printf "%s%s" $line . -}}
+  {{- $bytes = add $bytes (len .) -}}
+{{- end -}}
+{{- return printf "%s%s\r\n" $out $line -}}