Req: Support *.ttsmod archive format

[bobpaul]

The tool 'TTS Mod Downloader' fills the same needs as TTS-Manager, but is closed source, only works on Windows, and has a slightly different archive format. Where TTS-Manager uses PKZip archives with some some meta data in the comment field, 'TTS Mod Downloader' seems to be simple PKZip files with a different extension.

It would be nice if TTS-Manager could import these files. This might require adding options to the import command.

[bobpaul]

This might effectively be a duplicate of #10

[bobpaul]

you know, we can just parse the json file and I think that tells us everything (and more) than the meta data, anyway.