Add use of algorithm switch

DisPass has supported more than one algorithm for some time already,
but how to specify which algorithm to use was not quite clear. Now it
should use the correct algorithm and when specifying an unknown label
it will ask for the preferred algorithm.
Add use of sequence number switch

When dealing with an unknown label, creating a new label or adding a
label to the label file, ask for a sequence number and pass it to
DisPass. Only the `dispass2' algorithm uses this, but the `dispass1'
algorithm ignores it, so it shouldn't be a problem to just always send
it. Eventually the capabilities of each algorithm should be gathered
from DisPass itself.
Remove debugging `prin1' statement

Should not have been left in there.
Add support for the -f switch

The option `dispass-labelfile' specifies the labelfile you would like
to use instead of the one provided by DisPass itself.

These changes should be cleaned up later, but for now it works.