Fixed PySide issues by removing itemChange methods from GraphicsWidget and ViewBox;
Workaround is for ViewBox to see whether its scene has changed every time it paints.

Fixes: 12
Fixed running `python examples --test` for python3; needs to be tested under windows.
Fixed RemoteGraphicsView on windows
 - Avoid using authkey on windows; seems to be broken
 - Included yet another method of accessing shared memory as QImage
Fixed RemoteGraphicsView passing mouse events on python3 + pyside
Don't copy the context menu of ViewBoxes.

This allows customization of the context menu of a ViewBox simply by
calling viewbox.menu.addAction(...).  See issue #13.  Also some cleanup.
Fixes for multiprocess / RemoteGraphicsView:
- Process now optionally wraps stdout/stderr from child process to
  circumvent a python bug
- Added windows error number for port-in-use check
- fixed segv caused by lost QImage input in pyside
Override ViewBox.popup() to update menu before showing
Extend ViewBox menu in examples/contextMenu
Fixed unicode handling in AxisItem label
Merge branch 'axis_unicode_fix' into develop
Use actions of ViewBox's contextMenu in full menu.

The main change is on `ViewBox.getContextMenus`, which now returns an
up-to-date of actions that `GraphicsScene.addParentContextMenus` can use.

Also, `getContextMenus` was given a default implementation in the base
class (falling back on `getMenu` if defined), and some cleanup was done.
Fixed ViewBox not updating immediately after call to setAspectLocked
removed unnecessary scipy import
avoid division by zero when ViewBox has size or aspect = 0
fixed context menu handling for non-GraphicsItems
Merge branch 'dont-copy-context-menu' into develop
This allows ViewBox context menus to be modified by directly manipulating ViewBox.menu