QDateTime represents a specific point in time, so arithmetic
with durations makes perfect sense.
Moreover, we can finally equip QDateTime with a subtraction
operator, to calculate the duration between two QDateTime
objects.
[ChangeLog][QtCore][QDateTime] QDateTime now supports arithmetic
between QDateTime objects and std::chrono::duration objects.
A duration can be added to or subtracted from a QDateTime, yielding
another QDateTime; and two QDateTime objects can be subtracted
from each other, yielding the duration between them.
Change-Id: I656419f3bb9418c49f0e2fd0800c3dbaaf6aff32
Reviewed-by: Edward Welbourne <edward.welbourne@qt.io>
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>