Allow sending message without subject #24
Description
When I watch received messages in mcabber, I see it like below. Even if --subject arg is not used, it still sends empty subject (see []). It would be handy to be able not to send subject field altogether.
#[C] #dragonbox-pyra │09-08 21:01 <== []
[x] #elinux │ test
[C] #ffmpeg │
[C] #ffmpeg-devel │09-08 21:04 <== [subject]
[x] #gentoo │ test
[C] #gentoo-arm │
[C] #gentoo-embedded │09-08 21:06 --> hey
[C] #gentoo-hardened │09-08 21:06 <== [subject]
[x] #gentoo-kde │ test