cff-to-opencog perl parser version bug fix

Some small bug fixes
Ahh, OK, I'm doing some archeology... costs have been floating point for 5-6 years, I think, but the Java API had that as ints until version 5.1.1 that came out in Sept 2014 -- i.e. just 3 months ago.  No one noticed that they were ints until some parses started failing recently.  So the actual change to float in the Java API is recent.

I'm not sure how to deal with the backward-compat issue here.