Changed the serialization design. Now there's XmlSerializer, which is a separate, regular class. It's instantiated in trait 'ReminderDeserializer' (in TypedResources.scala), which can be mixed in into classes that are Android's 'Context', and can be used as a mixin.

Added try-with-resources, which mirrors 'using' construct from C# in Utils.scala

Changed the expandable list child items' layout to regular text views from checkboxes.