Enabled Webuntis Holiday query

Implemented Holiday view in Timetable
Hide other special time regions like breaks when shown in holiday

lib/extensions/dateTime.dart

@@ -0,0 +1,5 @@
+extension IsSameDay on DateTime {
+  bool isSameDay(DateTime other) {
+    return year == other.year && month == other.month && day == other.day;
+  }
+}