Ensure Multiple works with unset MaxFile option
Ensure Multiple works with unset MaxFile option

When MaxSize is not set (and defaults to zero) hashes were not being
calculated correctly, and when compareOnMatch == false would be
returning false positives.

Addresses GH issue #4, which was caused by PR #2

Further work to put file size determination before hash calculation can
tighten the maxSize bound, but for now this should ensure that
zero-length hashes aren't being computed.

udhos/equalfile,udhos/equalfile