Instrument directory search tools

[dgobbi]

Several of the command-line tools use the vtkDICOMDirectory class to scan a directory tree for files matching a query. Often these directory trees are large, and the scans can be slow. Currently, the only performance feedback provided to the user is a progress meter that goes from 0% to 100%.

It would be useful to have a verbose mode that shows which DICOM file is being read, and perhaps even additional information such as how many bytes were read and which was the last tag in the file that was read (the latter information would have to come from vtkDICOMParser).

One of the things I'm also interested in knowing is what query is being applied when the files are read. Usually the same query is used for several files, so the query would be logged before the files. Then each filename could be followed by a "Q" in the log to indicate that the query was applied while reading it.