This happens during debugging session in an IDE (eric5) when debugger inspects
variables but self._scenePos is not yet initialized.

  - Reduces aliasing when zoomed out
  - Improves performance and memory usage for large images
Merge branch 'image_downsampling' into develop

Conflicts:
	pyqtgraph/graphicsItems/ImageItem.py

 - Allow non-ndarray image data
 - Make quickMinMax a normal method

BF: unicode fix for TableWidget

Setting a table item value to a unicode value with non ascii chars would
cause the tablewidget contents to not be displayed (no exception thrown
either).

Changed all instances of str(..) or map(str,...) to use asUnicode and
issue seems to be fixed

Inverted MeshData.cylinder normals

Adds MeshData.cylinder

- Renamed GraphicsView signals to avoid collision with ViewBox signals that
  are wrapped in PlotWidget: sigRangeChanged => sigDeviceRangeChanged and
  sigTransformChanged => sigDeviceTransformChanged.
- All signal disconnections that catch TypeError now also catch RuntimeError
  for pyside compatibility.

Adds ViewBox.setLimits method

Conflicts:
	examples/SimplePlot.py

 - isosurface works for arrays with shapes > 255
 - Fixed ImageItem exception building histogram when image has only one value
 - Fixed MeshData exception caused when vertexes have no matching faces
 - Fixed GLViewWidget exception handler

ArrowItem: setStyle now combines new options with previously-set options.
AxisItem: fix minor exceptions

Renamed args for clarity, improved documentation
Fixed interaction bugs
 - zooming works correctly when view is against limit
 - no more phantom target range; target is reset during mouse interaction.

Import and py3 bugfixes for MultiPlotWidget
Add setMinimumPlotHeight method.

Merge remote-tracking branch 'termim/develop' into multiplotwidget-fix

Minor setup corrections