[PATCH] VIM: Add better attachment support

[Ian Main]

Franz Fellner wrote:
> It works as described. But IMHO it would be better to prompt the user to
> enter the location where he wants to save the attachment(s). This path
> could be taken if s:notmuch_attachment_tmpdir_default is set to empty.
> Or implement a different function for "save to".

It would be easy to add a filename prompt for saving a specific attachment.
I can preload it with the default value and it'll just mean one more keystroke
if that location is ok with you.

Sound good?

    Ian