Many style/formatting edits.
Bug fixes.
Reverted some previous changes temporarily while reviewing new code.
Merged Baker's "virtual device" in a simpler form. ODS2 will assign a sensible
drive name when mounting /image (== /virtual). If a specific drive name
is desired, mount /image drivename=filespec.
Files can be quoted, or use set qualifier_style unix if slashes are a problem.
Note that mount on the command line allows tab completion.
Moved "statistics" command into show.
Coded support for import/binary (fixed records, 512 bytes).
Converted fgets to fgetline
Added show devices for Unix (limited by standard APIs)
Got rid of separate ODS2-Image build.
