Give file readers access to previous base data properties

This can be beneficial when reading files from an MITK scene file.
For example, if properties are provided, the previous locations
of files in an MITK scene can be retrieved to resolve relative
paths to external data files.

This optional feature consists of three changes:

1. Deserialize base data properties before data in the scene reader
2. Extend the IFileReader interface to provide access to properties
3. Add another overload to IOUtil::Load() to pass properties to readers