Add right-click file option

[fossum]

It would be nice to open in the extension by right-clicking a file. I can think of two good use-cases.

1. User has extension set to normally download file and would like to manually trigger extension instead of automatically doing so.
2. For unsupported extensions, user could right-click and send to plugin.

[uri200]

+1 on this. Sometimes url do not have an extension. Right now there is no way to trigger the pluggin if the extension of the file doesn't match any of the supported types

Good job btw!