The API is nearly the same as QFutureSynchronizer.
The differences are:
1. We don't make this class a template class, however,
we are leaving some template methods, like addFuture().
For the scope of future synchronizing there is no need
for QFuture<T> API, the QFuture<void> is sufficient.
2. Renamed cancelOnWait() getter to isCancelOnWait()
in order to conform more to Qt API naming rules.
3. Removed futures() getter and provided isEmpty() instead.
4. Removed c'tor that takes a future and setFuture().
These 2 methods were superfluous and may easily be
substituted with other methods from the existing API.
The additional feature is about flushing finished futures.
This can be done on demand by a call to flushFinishedFutures(),
or is done automatically on every call to addFuture().
Change-Id: I6a323c9481eeeea9235e6b6e3048cef02873da08
Reviewed-by: Eike Ziller <eike.ziller@qt.io>
