[Azoth Sarin] Emit file transfer progress.
[Azoth Sarin] Handle TOX_FILECONTROL_KILL in waiting.
[Azoth Sarin] Support aborting file transfer during transferring.
[Azoth Sarin] Refactored to HandleKill().
[Azoth Sarin] Missing break.
[Azoth Sarin] Handle pauses.
[Azoth Sarin] Handle kills in paused state.