- 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.
