Saving sent attachments to data dir

[maximbaz]

What do you think about saving sent attachments into the data dir, together with the received attachments? This way we can open them afterwards, just like we can see the received ones.

Same would apply for images sent from clipboard, we'd save them into the data dir to be able to revisit them later.

[boxdot]

I think this is a great idea. It makes handling of attachment symmetric.