- 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.
The main change is on `ViewBox.getContextMenus`, which now returns an
up-to-date of actions that `GraphicsScene.addParentContextMenus` can use.
Also, `getContextMenus` was given a default implementation in the base
class (falling back on `getMenu` if defined), and some cleanup was done.
- GraphicsItem.pixelVectors copies cached results before returning
- Multiprocess fixes for Windows:
- mmap/shm uses anonymous maps rather than tempfiles
- avoid use of getppid and setpgrp
- work around hmac authentication bug (use os.urandom to generate key)
- AxisItem shows 2 tick levels instead of 3
- Lots of boundingRect and dataBounds caching
(improves ViewBox auto-range performance, especially with multiple plots)
- GraphicsScene avoids testing for hover intersections with non-hoverable items
(much less slowdown when moving mouse over plots)
These are deep changes; need good testing before we release them.
