* demo/viewer/Makefile.am: Add new files.

	* demo/viewer/main.cc: Initialize libMagick++.

	* demo/viewer/step_widget.cc,
	* demo/viewer/step_widget.hh: Improve interface.

	* demo/viewer/viewer.cc,
	* demo/viewer/viewer.hh,
	* demo/viewer/viewer.hxx: Handle calls to the DIA toolchain.

	* demo/viewer/preprocess.cc,
	* demo/viewer/preprocess.hh,
	* demo/viewer/process.cc,
	* demo/viewer/process.hh,
	* demo/viewer/runner.cc,
	* demo/viewer/runner.hh: New.