Major merge with dev branch; this branch is ready to become stable after 
a few rounds of bugfixes.
Fixed example testing on windows
Bugfixes:
  - AxisItem did not update grid line length when plot stretches
  - Workaround for PySide/QByteArray memory leak
Flowcharts get cubic spline connectors
bugfix: ignore inf and nan when auto-ranging
added experimental opengl line-drawing code
merge with inp
Pylint cleanups - remove commented out code, fix formatting etc
Some extra bits - add sizeHint, make not editable, make columns sortable
bugfix: examples working in PyQt 4.9.6 (workaround for API change)
Move setSortingEnabled to the widget init rather than after setting the data, otherwise weird sorting happens
Merged TableWidget updates from Laugher
TableWidget updates:
  - Made numerically sortable
  - Added setEditable method
  - Added example
merged updates from acq4
merged with inp branch
Added PolyLineROI.getArrayRegion
Check for length=0 arrays when using autoVisible
bugfix: prevent auto-range disabling when dragging with one mouse axis diabled
AxisItem bugfix: corrected x-linked view update behavior
Added MultiplePlotAxes example
merged updates from acq4
merged with inp