Faster than QgsGeometry::isGeosEmpty() because it avoids the
conversion to GEOS geometries and just uses the QgsAbstractGeometry
subclasses directly.
Also implements faster isEmpty() overrides for specific
QgsAbstractGeometry subclasses.
Make nCoordinates virtual, and provide shortcuts for some
geometry types. The base method which calls coordinateSequence()
is quite slow in certain circumstances.
Speeds up rendering point layers by ~25%, also likely to
speed up lots of geometry heavy operations throughout QGIS
Refs #15752
* Make closestSegment() behave as expected by QgsGeometry::closestSegmentWithContext
This fixes a bug that QgsPointLocator::nearestEdge() would return valid match even for point layers.
* Shortcut if using QgsPointLocator with a wrong layer type
