Format url links in event descriptions making them clickable

This allows to click through links in events in description fields
wherever the description field is displayed from libkcal.
This is useful since links to virtual meetings are often attached in the
description field in recent years

Signed-off-by: Calvin Morrison <calvin@pobox.com>
Signed-off-by: Michele Calgaro <michele.calgaro@yahoo.it>
(cherry picked from commit 8c92599470)

libkcal/incidenceformatter.cpp

@@ -575,9 +575,22 @@ static TQString displayViewFormatEvent( Calendar *calendar, Event *event,
   }
 
   if ( !event->description().isEmpty() ) {
+    TQString description = event->description();
+
+    // Regular expression to match URLs
+    TQRegExp urlRegex("https?://[^\\s]+");
+
+    int pos = 0;
+    while ((pos = urlRegex.search(description, pos)) != -1) {
+      TQString url = urlRegex.cap(0);
+      TQString link = "<a href=\"" + url + "\">" + url + "</a>";
+      description.replace(pos, url.length(), link);
+      pos += link.length();
+    }
+
     tmpStr += "<tr>";
     tmpStr += "<td><b>" + i18n( "Description:" ) + "</b></td>";
-    tmpStr += "<td>" + event->description() + "</td>";
+    tmpStr += "<td>" + description + "</td>";
     tmpStr += "</tr>";
   }