Added antialiasing to GL line items

  - better handling of tick text / label area
  - ability to truncate axis lines at the last tick

Added style options to flowchart connection lines
SVG export bug - correctly handle coordinate corrections for groups with mixed elements
Updates to ScatterPlotWidget, DataFilterWidget, and ColorMapWidget
Added exit() function for working around PyQt exit crashes
Bidirectional pseudoScatter for beeswarm plots
Added several examples
Added BarGraphItem
Fixed GraphItem antialiasing
Added parentChanged and viewChanged hooks to GraphicsItem
Made LabelItem a subclass of GraphicsWidgetAnchor
Documented planned features for PlotDataItem (these should be fixed before next release)
ScaleBar complete rewrite
Re-fixed crash bug in ScatterPlotItem
fixed scatterplotitem antialiasing

added panning plot example

Added MultiplePlotAxes example

  - Made numerically sortable
  - Added setEditable method
  - Added example

Move setSortingEnabled to the widget init rather than after setting the data, otherwise weird sorting happens

added experimental opengl line-drawing code

  - AxisItem did not update grid line length when plot stretches
  - Workaround for PySide/QByteArray memory leak

Workaround for PySide bug; fixes GradientEditorItem

cleaned up examples

CSV exporter gets 'precision' option