compileFilters takes a list of regular expression strings and compiles them into a [FilterSet].

DownloadFile places the contents of the given url into a local file at the given path with the given mode.

NewDirectory wraps os.Mkdir to provide standardized directory creation and logging.

NewFileFrom wraps os.OpenFile and io.Copy to standardize the way the package creates output files.

NormalizeFilePath is a utility function that rewrites file paths specified to ensure that they are relative to the current working directory and don't have names that are potentially a nuisence for users (such as names composed only of whitespace characters, only dots, etc.).

FilterSet contains compiled regular expressions which identify files to be selected.