[Fix #7405] Graduated renderer: Feature count 0 with scale or rotation
[pyqgis-console] uses QFileInfo instead of os.path to check if file exists
- minor fixes and cleanup
drop qgis_help.db and debian packaging update
raster resampler fixes, use zoom in resampler also for oversampling 1
Merge pull request #592 from matthias-kuhn/fix-7405

[Fix #7405] Graduated renderer: Feature count 0 with scale or rotation
Update labeling gui and add expression support as data defined value

- Add QgsDataDefined class
- Add QgsDataDefinedButton class
- Add data defined Python support
- Add standalone SVG selector dialog to QgsSvgSelectorWidget class