Extract distribution name and version from a distribution filename

Many online services that are centered around CPAN attempt to associate multiple uploads by extracting a distribution name from the filename of the upload. For most distributions this is easy as they have used ExtUtils::MakeMaker or Module::Build to create the distribution, which results in a uniform name. But sadly not all uploads are created in this way. CPAN::DistnameInfo uses heuristics that have been learnt by http://search.cpan.org/ to extract the distribution name and version from filenames and also report if the version is to be treated as a developer release.