This interface can be implemented by users (there are no implementations in Saxon itself). It is
used only when Saxon is invoked from the command line, and the -init:class option is used on the command
line to nominate an implementation of this class. The initialize() method of the supplied class will
then be called to perform any user-defined initialization of the Configuration.
The initializer is invoked after all other options on the command line have been processed; the initializer
can therefore examine the Configuration to see what options have been set, and it can modify them accordingly.