optimize ScatterPlotItem with pxMode=True
Correct comment in examples/ScatterPlot.py
Modify for loop into map in ScatterPlotItem.py
Improve ScatterPlotItem
Slightly faster and more memory efficient, correct python 3 bug
Some few more optimization to ScatterPlotItem
Rename self.tar to self.target
Improve ScatterPlotItem.py
Add optimization for PySide, Plot only visible symbole, cache rectTarg
Clean ScatterPlotItem
Correct symbols position
Merge remote-tracking branch 'gpoulin/scatter_optim' into scatter-optim

Conflicts:
	pyqtgraph/functions.py
	pyqtgraph/graphicsItems/AxisItem.py
cleanups
cleanup; corrected view clipping.
more cleanups
added simple test
Major performance improvement for ScatterPlotItem

Merge branch 'scatter-optim' into develop