If the text was more lines that the height of the active region in the dialog
the 2 last lines were not displayed.

 * Prefix all private methods with _
 * Write missing docstrings
 * Move all public methods above the private ones
 * Add module docstrings where missing
 * Define source code encodings on all modules

If the image gets registered as public allow anyone to read the
metadata and the md5sum file.

This is a workaround for a progress bar bug, where the system may
stay with the cursor hidden if finish() is not called.

Add progress >= 1.0.2 as install_dependency, since this is the version
that fixed the empty progress bar problem.

Also move it to a separate module.

Logging can be enabled using the -l input option

In the cli output classes this method will clear terminal screen if
the standard output is a terminal.

Also fix various issues. snf-image-creator-dialog is almost ready.
Some `Help' entries are missing.

Also create a new output class (InfoBoxOutput) to be used when
performing syspreps