Added PyplotViewer command support
Colormap limit setting in PyplotViewer
Only one coroutine creation per PyplotViewer instance
Colormap support in PyplotViewer added
PyplotViewer is pausable
Base pyplot updater class added
PyplotImageViewer added instead of PyplotViewer

PyplotViewer is now a base class for more viewer types.
Don't let the exception in redraw hook escape unnoticed
PyplotCurveViewer for 1D data drawing added
Title added to PyplotViewer classes
Add label text to axes in PyplotCurveViewer

The label is extracted from quantity if the data have any,
if not the labels remain empty.
Pyplot viewers CHANGES update