Deprecated the pause-related APIs of QFuture* classes and
added alternatives having "suspend" in the name instead.

With 2f15927f

 new
isSuspended()/suspended() APIs have been added to QFuture* classes for
checking if pause/suspension is still in progress or it already took
effect. To keep the naming more consistent, renamed:

 - setPaused() -> setSuspended()
 - pause() -> suspend()
 - togglePaused() -> toggleSuspended()
 - QFutureWatcher::paused() -> QFutureWatcher::suspending()

Note that QFuture*::isPaused() now corresponds to (isSuspending() ||
isSuspended()).

[ChangeLog][Deprecation Notice] Deprecated pause-related APIs of
QFuture and QFutureWatcher. Added alternatives having "suspend" in
the name instead.

Change-Id: Ibeb75017a118401d64d18b72fb95d78e28c4661c
Reviewed-by: Mårten Nordheim <marten.nordheim@qt.io>
Reviewed-by: Leena Miettinen <riitta-leena.miettinen@qt.io>
Reviewed-by: Andrei Golubev <andrei.golubev@qt.io>
Reviewed-by: Jarek Kobus <jaroslaw.kobus@qt.io>