An interface to be implemented by property editors which want to provide
a load/store of property values in human-readable XML.
The XML persistence is currently used by the form editor module for storage of
modified property values.
Called to load property value from specified XML subtree. If succesfully loaded,
the value should be available via the getValue method.
An IOException should be thrown when the value cannot be restored from the specified XML element
element - the XML DOM element representing a subtree of XML from which the value should be loaded
IOException - thrown when the value cannot be restored from the specified XML element