#24 fix -T option

[Egbert Eich]

The attached patch 'fixes' the -T option: currently the
test for missing total track number is wrong and the
results of the string manipulation are just ignored and
discarded.
The fix tests if a total number of tracks was
specified. If not it tries to collect this from the
existing data if available.

[Egbert Eich]

Patch as described.