PyPlot updates from Oliver Schoenborn:

PyPlot updates from Oliver Schoenborn:
    - Factored out "draw command" so extensions easier to implement: clean
      separation b/w user's "draw" (Draw) and internal "draw" (_draw)
    - Added ability to define your own ticks at PlotCanvas.Draw
    - Added better bar charts: PolyBar class and getBarTicksGen()
    - Put legend writing for a Poly* into Poly* class where it belongs
    - If no legend specified or exists, no gap created

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@30293 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775