Integrate patch for --ignore-dir=match:...

See also GH #42
Update changelog
Work on more tests for --ignore-dir
Add stub for --ignore-file testing
Use filter facility for --ignore-dir and --noignore-dir
Remove stringification overload for Filters

This is for debugging purposes anyway, and it messes with boolification
of filters
Remove redundant check

App::Ack::Resource::Basic::new can no longer return a falsy value,
since files are opened lazily.
Add IsPath filter

For implementing --ignore-dir in terms of relative paths
Use IsPath for --ignore-dir matches
Add IsPathGroup module
Enable usage of IsPathGroup
Add a directory with extension to the test corpus

This is so we can test --ignore-dir=ext:.d down the road
Fix broken tests from dir.d addition
Uses lists_match instead of is_deeply for ack-n.t

This gives us more diagnostic information in case of failure
Add test for --ignore-dir=ext:...
Make sure ext:... works with --ignore-dir
Fix broken ack-n.t

lists_match needs messages, it seems
Add test for --ignore-dir=firstlinematch:...
Don't allow filter types that we said we wouldn't
Be less specific in allowing filter types for --ignore-dir in the config loader