Follows a useful change added in the kwaylandScanner tool the
s_version becomes part of the Private class.
Also fixes the related generation in the tool.
The shadow protocol is inspired by the KWin's X11 protocol and the
DecorationShadow in KDecoration2.
A shadow is attached to a surface (after a commit on surface) and
consists of several image parts (represented through a buffer):
* top-left
* top
* top-right
* right
* bottom-right
* bottom
* bottom-left
* left
In addition there is an offset on each side.
For more information see also the X11 protocol described at [1].
Note: the protocol is currently missing documentation and changing
the shadow is not yet properly delegated to the server API.
[1] https://community.kde.org/KWin/Shadow