Fix examples to new style

Many demos are using an old style with lots of code smell. Clean these up. AFAIK the following grep gives the bad examples.

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| [05-20 17:05] aterrel@lilac:~/workspace/chaco/examples (.132 Mb) (fixing_demos)
$ grep -r "class Demo(HasTraits)" *
advanced/data_stream.py:class Demo(HasTraits):
advanced/javascript_hover_tools.py:class Demo(HasTraits):
advanced/spec_waterfall.py:class Demo(HasTraits):
advanced/spectrum.py:class Demo(HasTraits):
advanced/variable_sized_scatter.py:class Demo(HasTraits):
basic/bounded_grids.py:class Demo(HasTraits):
basic/candle.py:class Demo(HasTraits):
basic/cmap_image_plot.py:class Demo(HasTraits):
basic/cmap_image_select.py:class Demo(HasTraits):
basic/cmap_scatter.py:class Demo(HasTraits):
basic/contour_cmap_plot.py:class Demo(HasTraits):
basic/contour_plot.py:class Demo(HasTraits):
basic/draw_layers.py:class Demo(HasTraits):
basic/grid_container.py:class Demo(HasTraits):
basic/grid_container_aspect_ratio.py:class Demo(HasTraits):
basic/image_inspector.py:class Demo(HasTraits):
basic/image_lasso.py:class Demo(HasTraits):
basic/image_plot.py:class Demo(HasTraits):
basic/inset_plot.py:class Demo(HasTraits):
basic/line_drawing.py:class Demo(HasTraits):
basic/line_plot1.py:class Demo(HasTraits):
basic/line_plot_hold.py:class Demo(HasTraits):
basic/log_plot.py:class Demo(HasTraits):
basic/nans_plot.py:class Demo(HasTraits):
basic/polygon_move.py:class Demo(HasTraits):
basic/regression.py:class Demo(HasTraits):
basic/scatter.py:class Demo(HasTraits):
basic/scatter_custom_marker.py:class Demo(HasTraits):
basic/scatter_inspector.py:class Demo(HasTraits):
basic/scatter_select.py:class Demo(HasTraits):
basic/scatter_toggle.py:class Demo(HasTraits):
basic/scrollbar.py:class Demo(HasTraits):
basic/zoomable_colorbar.py:class Demo(HasTraits):
bigdata.py:class Demo(HasTraits):
data_labels.py:class Demo(HasTraits):
data_view.py:class Demo(HasTraits):
edit_line.py:class Demo(HasTraits):
financial_plot.py:class Demo(HasTraits):
financial_plot_dates.py:class Demo(HasTraits):
functionplotter.py:class Demo(HasTraits):
multiaxis.py:class Demo(HasTraits):
multiaxis_using_Plot.py:class Demo(HasTraits):
quiver.py:class Demo(HasTraits):
range_selection_demo.py:class Demo(HasTraits):
scales_test.py:class Demo(HasTraits):
simple_line.py:class Demo(HasTraits):
simple_polar.py:class Demo(HasTraits):
stacked_axis.py:class Demo(HasTraits):
tornado.py:class Demo(HasTraits):
tutorials/scipy2008/ploteditor.py:class Demo(HasTraits):
two_plots.py:class Demo(HasTraits):
vertical_plot.py:class Demo(HasTraits):
zoomed_plot/zoom_plot.py:class Demo(HasTraits):