Enable easy recovery of sending stuff that looks like a command
Bug description
When I'm chatting, and I try to send "/o/", Gajim complains (rightfully so) about an unrecognised command. Right now, I have no easy option to send my message, because right now I'd have to press Ctrl+Up, Home, (Shift+7 to get a slash), Ctrl+Enter. Note that the Home key might be awkwardly placed on a laptop.
I expected to really send the stuff using Ctrl+Shift+Enter or smth similar. That would dramatically ease up the resending process, because I'd only have to press Ctrl+Up, Ctrl+Shift+Enter.