preparing for Travis CI integration
fix unused sprintf arguments in carpf tests

This seems to have caused some failures on perl-5.21.1.
fixes gh#4: stringification of negative zero

older Perls might stringifiy negative zero as "-0",
which caused some tests for _::floor and _::ceil to fail.
fixes gh#3: "ref_type" with regexes for perl < 5.11

Older perls think that regex-references are scalar references. This
commit patches _::ref_type for older perls to return "REGEXP" if "ref"
returns "Regexp". This isn't ideal, but is better than the alternative.
preparing release 1.2.0_1