- Actually share identical pixmaps in memory
- Cache them inside a dedicated QPixmapCache
- Render identical symbols in a batch using
  QPainter::drawPixmapFragments()

Batch rendering can be disabled via the
BATCH_RENDERING define.

The "O"-keystroke-debug mode is now extended
by displaying a background color for each
placemark. Placemarks rendered in parallel
share the same background color.

This should benefit rendering of huge amounts of
pixmaps of the same kind (e.g. trees).

Deleted placemarks (e.g. tile removed in vector osm) were kept in
the cache forever with their visible placemark counterpart only being
deleted on a style change (~map theme change). Placemarks that moved
out of the viewport but not being deleted directly however had their
visible placemark counterpart deleted directly, leading to a costly
recreation when the placemark moved back into the viewport soon after.

Now visible placemarks are cached only in an area around the viewport,
and eventually cleaned up when their placemark counterpart is deleted.

Lazy label pixmap creation is useful since some placemarks will never
have their label shown, its creation however is rather costly due to
the painter path involved (with glow style).

- toggle with key 'O' (Marble needs to be run with --debug-info)
- red rectangles are hidden placemarks
- blue rectangles are bounding boxes of visible placemarks
- green rectangles are symbol and label bounding boxes of visible
  placemarks
- green text is placemarks' popularity (sort key used to decide
  which ones to show/hide on collisions)

Some red rectangles seem to get stuck. This is not a bug in the debug
painting, but the viewport cache not working properly and keeping
many orphane placemarks around forever. Needs to be fixed in a
follow-up commit.

CCMAIL: tackat@kde.org

Fixes warnings about using automoc in relaxed mode which was required
for keeping compatibility with older cmake versions. Minimum cmake
version is now 2.8.6.

REVIEW: 124333

Replaces PhotoOverlay visualisation on the globe with a Google Earth like.
This means it shows the icon of the overlay's style on the globe and shows
the actual image after click in a popup.

Data needed for rendering (texture tiles, search results, routes, ...)
is often download from the Internet and Marble renders preliminary
results while waiting for the data to arrive. The preliminary results
are created in various ways, e.g. using old (outdated) data, higher
level tiles or partial data. We inform the user to some extend about
pending data (e.g. progress bar for tile downloads, busy indicator for
routes), but there is no sane programmatical way at the moment to
determine whether all data has arrived yet.

The patch adds an enum property RenderStatus { Complete,
WaitingForUpdate, WaitingForData, Incomplete } to MarbleMap and
MarbleWidget along with a renderStatusChanged() notification signal.
LayerManager maintains that status value. Internally it delegates the
status determination to all layers and uses a tree-like data structure
to record all details.

REVIEW: 118618

Moves files and directories:
1) src/lib => src/lib/marble
2) src/*marble-qt related* => src/apps/marble-qt
   src/*marble (KDE) related* => src/apps/marble-kde
   src/qt-components/marble-touch => src/apps/marble-touch

1) is a preparation to align the structure of installed headers with
the structure of the library sources, so that we can build tools and
examples in the same go and detect API changes early.
2) results in a much more tidy src/ and more intuitive location of the
sources of the respective applications.

REVIEW: 112114

also simplify repeatX and repeatableX

REVIEW: 108636

Each Layer can override the QString runtimeTrace().
The layerManager will display timing information and that trace.
The option is controlled by marble --runtimeTrace in qt and kde,
and also by widget()->setShowRuntimeTrace( true );

Some traces tailor-made for TextureLayer, GeometryLayer and PlacemarkLayer
are provided.

REVIEW: 105655

also move defaultLabelColor to GeoDataFeature which handles
the default styles already.

PlacemarkPainter: turn into layer and rename to PlacemarkLayer; reverse composition with PlacemarkLayout

PlacemarkLayout used to be both responsible for laying out placemarks and painting them.
After having determined the layout, it realized painting by delegating the acutal work to PlacemarkPainter.

By reversing composition, PlacemarkPainter would ask PlacemarkLayout to update the layout before it would paint the placemarks itself.
That way, PlacemarkPainter becomes a layer and PlacemarkLayout would be the layer's model, which is a common pattern in Marble.

REVIEW: 105152

font weight will be adjusted in drawLabelText()

BUG: 247859

REVIEW: 103777
BUG: 288297

BUG: 285853