[Azoth Sarin] Report task start before returning the QFuture.

Qt is utter crap.
[Util] Added NewType.
[Azoth Sarin] Added missing noexcept specifier.
[Azoth Sarin] Properly rethrow QtConcurrent exceptions.

Avoid slicing them to std::exceptions.
[Azoth Sarin] More debug info on toxav_call fail.