+* Improved documentation.
+* Upgrade bundled ion-c library.
+* Fix gh-issue #5: ion\Timestamp crashes with string timezones.
+* Add ion\Exception.
+* Refactor (un)serialization facilities:
+ * Removed ion\Reader\Options class and moved the options to the ion\Reader constructor.
+ * Removed ion\Writer\Options class and moved the options to the ion\Writer constructor.
+ * Renamed ion\Serializer\PHP to ion\Serializer\Serializer.
+ * Renamed ion\Unserializer\PHP to ion\Unserializer\Unserializer.
+ * Changed ion\Serializer::serialize(mixed $data) to
+ ion\Serializer::serialize(mixed $data, ion\Writer|array|null $writer = null).
+ * Changed ion\Unserializer::unserialize(string|resource $data) to
+ ion\Unserializer::unserialize(ion\Reader|string|resource $data)
+* Add support for custom (un)serializers.
+