wip:3D expression evaluation

* Added HDF5 exporter
* CSV exporter gets (x,y,y,y) export mode
* Updates to SVG, Matplotlib exporter
* Console can filter exceptions by string
* Added tick context menu to GradientEditorItem
* Added export feature to imageview
* Parameter trees:
    - Option to save only user-editable values
    - Option to set visible title of parameters separately from name
    - Added experimental ParameterSystem for handling large systems of
        interdependent parameters
    - Auto-select editable portion of spinbox when editing
* Added Vector.__abs__
* Added replacement garbage collector for avoiding crashes on multithreaded Qt
* Fixed "illegal instruction" caused by closing file handle 7 on OSX
* configfile now reloads QtCore objects, Point, ColorMap, numpy arrays
* Avoid triggering recursion issues in exception handler
* Various bugfies and performance enhancements

  - 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)

Added debian control files

updated versioning system 

Started new SVG exporter
Merged updates from ACQ4

Started new SVG exporter
Merged updates from ACQ4

  - use graphics system 'raster' by default
  - disable OpenGL in QGraphicsView

- Image exporter detects GraphicsView background color
- Corrected exporter filename handling for SVG export
- ViewBox no longer attempts to deregister itself while python is exiting
- Speedup for conversion using np.array(MetaArray_instance)
- GLGraphicsItem updates immediately when its GL options have changed
- Corrected some GL shader program bugs for nVidia drivers
- Fixed coordinate mapping bug in functions.transformCoordinates
- Fixed PySide import error

Reorganized shader programs
Infrastructure updates for OpenGL system

  - built in Christian Gavin's os.listdir replacement
  - added os.isdir replacement
Fixed ViewBox causing errors at shutdown

- 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

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

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

  - 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

- Text spacing fix for AxisItem

- Added pyqtgraph.systemInfo() for bug reporting
- GraphicsLayout does a better job of avoiding occupied cells when using automatic placement
- Fixed sizing issues with LabelItem
- Updated GraphicsLayout example

bugfixes for pyside-specific issues

Added workaround for Qt crash-at-exit bug (make sure that all GraphicsItems live in a scene before exiting)

Added SRTTransform3D

 - optional context menu for ImageItem
 - inverted y-axis in Canvas (+y now points upward)
 - extra __init__ arguments for Dock
 - Transform can be constructed from Matrix4x4
 - many others

fixes for flowchart
 - added missing FeedbackButton.py
 - corrected imports

 - HistogramLUTItem avoids using lookup table if possible
 - GradientEditorItem has a method to ask whether the gradient is trivial (can be applied without the use of a lookup table)
 - ROI, LinearRegionItem, InfiniteLine no longer redraw for every mouse movement