A "filled marker" is similar to the simple marker symbol layer, except
that it uses a fill sub symbol to render the marker. This allows use
of all the existing QGIS fill (and outline) styles for rendering
markers, eg gradient or shapeburst fills.
A new abstract class QgsSimpleMarkerSymbolLayerBase has been created
from which both QgsSimpleMarkerSymbolLayerV2 and
QgsFilledMarkerSymbolLayer derive. All common code has been moved to
this base class, allowing for easy addition of new shapes or features
to both simple markers and filled markers without duplication.
Also, adds a lot of missing docs to marker symbol layers.
Rationale:
- there was a lot of large objects passed by value, so potentially
there's a speed bump from this
- even for implicitly shared classes like QString/QList there's still
a (small) cost for copying the objects when there's no reason to
- it's the right thing to do!
- update methods of existing classes
- add comment to methods missing in the sip bindings
- split up collective sip files into single files and use
same directory structure in python/ as in src/
- add a lot of missing classes (some might not make sense because of
missing python methods in those classes)
- remove some non-existing methods from the header files
- add scripts/sipdiff
- replace some usages of std::vector and std::set with QVector/QSet
