Replace use of ChacoPlotItem with just Item and ComponentEditor

[rahulporuri]

There are a few examples which use ChacoPlotItem instead of the enable ComponentEditor. It is possible that the ComponentEditor came after the chaco ChacoPlotItem and related objects. I think we can rewrite the examples to use ComponentEditor instead of the chaco classes.

See related #640

[rahulporuri]

FTR, I spent a little bit of time on this and this is not a trivial task.