ContentIndexFilter: added abstract method getDescription() which returns
a description the implemented filter.

HiddenFileFilter, NameContainsFilter, PathContainsFilter,
ReadOnlyFileFilter, SizeCeilingFilter, SizeFloorFilter: implemented
getDescription().

ProgressWindow: removed unused status JLabel labelStatus, defined
behavior for selection of the stop button.

DetectionTask: migrated the main SwingWorker progress update (publish())
flags' behavior and migrated from a switch-case block to a more flexible
if-then block.