GitLab

- add a filter that defines rules for ignoring hidden and/or files
listed explicitly or defined in a gitignore file
- update SerialFile construct to accept a Filter

feat(add-file-ignore): fix tests, slight refactor

- add new SerialFile constructor with original signature for backward
compatibility
- update tests for new SerialFile behavior

feat(file-ignore):  cleanup code+tests

- address PR comments
- add more documentation
- use existing function for cross-platform hidden file detection
- be more consistent when checking for hidden fies
- add more examples+test cases

feat(file-ignore): rework `Filter` constructor

- add filter tests

feat(file-ignore): apply exclude rules lazily

- apply exclude rules from filter when iterating over dir contents
 instead of at serialFile construction time