made scipy optional in functions and ImageItem

- added ability for ScatterPlotItem to use arbitrary symbol shapes
- added scatter plot speed test for evaluating new methods
- added butterworth notch filter to flowchart library
- fixed bugs with ViewBox trying to close itself after python has started cleaning up
- fixed python 2.6 compatibility bug in PlotCurveItem
- fixed support for list-of-dicts and dict-of-lists input for PlotDataItem
- check to ensure Qt version is >= 4.7
- workaround for numpy segmentation fault
- several other minor updates and documentation changes

Fixed setup.py to automatically search for all sub-packages

 - initialize ImageItem.menu
 - fixed default argument for ROI.getAffineSliceParams(axes)

  - fixes for saveState / restoreState (better handling of custom parameter classes)
  - added method GroupParameter.setAddList
  - ListParameter now remembers its value even if its list is cleared and rebuilt
  - added ActionParameter (buttons) and TextParameter

Now detects and switches between PyQt / PySide automatically; no need to distribute different versions of the library anymore.

  - ROI.getArrayRegion makes sure the ROI and image share the same scene
  - Added a few binary operator methods to metaarray 
  - Fixed flowchart/eq.py handling of metaarray objects

  - fixed handling of foreground colors in AxisItem
  - fixed rare crash caused in AxisItem 
  - fixed improper propagation of key events from SpinBox
  - many others

Canvas: added clear() method

  - Fixed up parametertree.saveState() and restoreState() methods
  - Updated parametertree documentation

  - avoid sending keyboard interrupt signals to child processes
  - parallelizer keeps better track of processes that die unexpectedly
  - added ability to specify a different executable when starting new processes

 - flowchart emits state change signal when chart is loaded
 - metaarray workaround for lack of h5py debugging symbols

Minor documentation updates

  - Fixed some floating-point precision issues. (Added a workaround for QTransform.inverted() bug)
  - No longer putting asUnicode inside __builtin__ since this causes problems in some rare circumstances
    (pyshell, lazy import recipe)
  - Minor docstring updates

- AxisItem.setScale(1) works properly to disable auto-value-scaling
- OpenGL fixes (stack overflow when drawing items, improper call to glPopAttrib)

- Text spacing fix for AxisItem

Added script for reporting GL version info

- workaround for PySide exit crash
- fixed alpha of major/minor grid lines

Bugfix -- AxisItem enforces tick boundaries more strictly

minor code edits