#15 Add more info on the Dicom file browser

[Ofri Sadowsky]

For the Dicom file selection window (the dialog right
after directory selection, with preview etc.)

1. Enlage the file list window so that more filenames
can be seen simultaneously.
2. Consider adding additional information, either next
to the filenames or on the preview windows. This may
include slice position information, filename (for an
image), etc.
3. One nice way to do it when there is not enough
space on the display is to have a "Properties" item on
a context menu attached to each file or preview image.
It's generally quicker to use than just extract all
the header information and browse through it visually.