Increase coverage for DelimiterVersions listing algorithm to have it
in par with DelimiterMaster before attempting a fix: most existing
tests from DelimiterMaster have been copied and adapted to fit the
DelimiterVersions logic.

Enable the skip-scan optimization to work for DelimiterVersions
listing algorithm when used with a delimiter.

For this to work, instead of returning FILTER_ACCEPT when encountering
a version that matches the master key (which resets the skip-scan
counter), return FILTER_SKIP to let the skip-scan counter increment
and eventually skip the entire listed common prefix after 100 entries.

…' into tmp/octopus/w/7.10/bugfix/S3C-4275-versionListingWithDelimiterInefficiency

…iciency' into tmp/octopus/w/8.1/bugfix/S3C-4275-versionListingWithDelimiterInefficiency