We don't want various plugins to depend on the Help plugin,
but we also do not want Core to depend on QtHelp.
For example when turning the Help plugin off, documentation should
actually no longer be registered through QtHelp. So we need
parts of the interface in Core, which must then be delegated
to the actual implementation in Help.
As positive side-effects the interface in Core will be slimmer,
and the code in the Help plugin can later be simplified, too,
because then we don't have the "Core" and the "Gui" help engines
separated in different plugins anymore, which should remove the
need for some setup indirections.
Task-number: QTCREATORBUG-20381
Change-Id: I634c5811c45d6a3dfd6ddc682cae270e38384cbf
Reviewed-by: hjk <hjk@qt.io>
In case of split mode we did not check if the actual requested doc
exists and thus did fail to open the browser if it could not be found.
Reviewed-by: Daniel Molkentin
