Add support for DLC files

[elmolini]

Websites like filecrypt offer a "Click n' load" button or a DLC file. This is really useful when a file is splitted between various links. This button or DLC file automatically add/contain all of the download links and add them to you're download manager of choice.

I would love to have this feature on motrix, it's the only thing keeping me on jdownloader 2.

Afaik, only Jd2, pyloader and a couple more are compatible with this feature. It's not a "super popular" thing but I still think that's definitely useful.