Feature Request: Allow .txt files to be visible in the "Open Directory" hierarchy

[sbanville-delfi]

Currently, when opening a directory using File -> Open directory..., the file hierarchy panel filters out files with a .txt extension. Many users work with TSV or CSV data that is saved with a .txt extension.

Because Tad is already fully capable of parsing these text files (opened via the command line /Applications/Tad.app/Contents/MacOS/Tad mydata.txt), it would be incredibly helpful if .txt files were added to the list of allowed extensions in the directory watcher. This would prevent users from having to rename their external files to .tsv or .csv just to select them from the Tad hierarchy panel.

Alternatively, being able to allow Tad to see an open files without an extension would be great as I don't have control of external data and will receive files with extensions not currently supported.

Thanks!