[Feature] Support Drag and Drop

[Teraskull]

Dropping identity files and files to be encrypted directly on the window would be a good UX improvement.

Something similar to how https://github.com/HACKERALERT/Picocrypt handles Drag and Drop would be nice.

Thanks for the useful GUI!

[spieglt]

I'm not sure when I'll be working on a version 2 but I'll add this to the list, thanks for the feedback.