interactive: fix previous commit

wrong structure used

Signed-off-by: Marek Chalupa <mchqwerty@gmail.com>
interactive: implement edit command

This is simple command. It stores content of the message into temporary
file and than invokes and editor on that file. After the work is done,
the message is read back and use can send it further.

Signed-off-by: Marek Chalupa <mchqwerty@gmail.com>