Fixed linearRegionItem hilight when not movable

Started new SVG exporter
Merged updates from ACQ4

  - generalized makeARGB API: can now process arrays of arbitrary shape.
  - affineSlice automatically converts vector arguments to array
  - new function applyLookupTable taken from makeARGB
  - isosurface function returns array
Updated VideoSpeedTest example to follow new makeARGB API

LayoutWidget: row argument now accepts 'next' as value
ParameterTree bugfix: avoid infinite recursion when accessing non-existent attributes
ViewBox: avoid exit error caused when cleanup callback is invoked while python is shutting down

Added functions.transformCoordinates() for mapping numpy arrays of coordinates from QTransform and QMatrix4x4

Minor updates:
- fixed SRTTransform3D.matrix()
- ViewBox fix: updateAutoRange leaves unused axes completely unchanged
- documentation updates

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

  - 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

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

  GraphicsObject - corrected bug in viewPos() method
  WidgetGroup - allow bound methods in interfaces
  parametertree - fixed crash when calling remove from context menu