Rename QWaylandDecoration => QWaylandAbstractDecoration

This is in preparation for decoration plugins.

Change-Id: Idb322a7a5cbc2eb5bf2cce019073f9f4fb46297f
Reviewed-by: Robin Burchell <robin.burchell@viroteck.net>
QtWaylandClient: Pluginize window decorations.

Convert to a D-pointer, split between abstract base class and an implementation.

Also move implementation of the current built-in decoration to the "bradient"
plugin, named in glorious memory of the programmer-designed blue gradient that
will forever sear our eyeballs.

The decoration plugin may be specified using the environment variable
QT_WAYLAND_DECORATION.

Change-Id: Idc99ab06ae138ad299bad2b62b9595379bd007ab
Reviewed-by: Robin Burchell <robin.burchell@viroteck.net>
decorations: Remove strange set dance between QWaylandWindow & QWaylandAbstractDecoration.

This makes absolutely no sense. Just do things inline.

Change-Id: Ic6d4e62bc9b3c0a4533f63740f2608a0be201047
Reviewed-by: Robin Burchell <robin.burchell@viroteck.net>
Use the screen resolution to determine whether a screen is portrait

We were using the screen physical size to determine if a screen is
portrait or landscape, but we may not always get a valid size.
Instead use the screen resolution.
The orientation is then calculated in the wl_output.done handler,
since we don't know the resolution yet when receiving the first
wl_output.geometry event.

Change-Id: I3554f916e54db829f49fa3d1ea24f7ce1ff24e7c
Reviewed-by: Gunnar Sletta <gunnar@sletta.org>
MER: Add packaging.
MER: cmake unscrew

Change-Id: I92d57630933dacaed1e60805105adc0aae5aa2a2
MER: HACK: Don't use QWaylandInputContext

We want to use Maliit.

Change-Id: I10d50229a131feeb3c10d061aac5d805bb936849
[packaging] Add versions to some build dependencies

Change-Id: I32fe1a7101438bf425b18259413258377f3ee92d
MER: Revert "Support RasterGLSurface windows"

Qt 5.2 does not have the RasterGLSurface window type
This reverts commit b743fc7a1e6ee680ca89ae17fb6b521178fd09a9.
MER: Revert "The QWindowSystemInterface API changed, make it build again"

Make it build with Qt 5.2 instead of 5.4
This reverts commit a7d9523c9cf731f3f6dd9424fc409eb315800153.
MER: Don't install the decoration plugin