When using the qdbus interface of yakuake, the following warning is constantly printed in the terminal:
`Skipped method "addSession" : Unregistered input type in parameter list: Session::SessionType`
That's because the `enum Session::SessionType` is the type of parameter that is accepted by the `addSession` function that is exposed through the dbus interface, and this `enum` hasn't been registered (with a `Q_DECLARE_METATYPE`?).
As I see, registering a new metatype can be a bit tricky, and I guess this is the reason why the additional functions `addSessionTwoHorizontal()`, `addSessionTwoVertical()` and `addSessionQuad()` exist: simplified code. After all, these functions are just one-line-code wrappers of the existing `addSession()` function (they call the addSession() with different session type parameter).
This patch renames the existing `int SessionStack::addSession(Session::SessionType type)` function to `SessionStack::addSessionImpl(Session::SessionType type)`, and creates a yet-another-wrapper function `int SessionStack::addSession()` without any parameters to make it available through the QDBus interface in order to suppress these warnings without breaking the DBus API. The newly added `addSession()` behaves exactly as the old addSession() behaved; just creates a new `Session::Single` type session.