Merge pull request #36 from rsrock/master

Test and doc updates
change redraw event to draw and resize
add draw(Canvas)
Fix the libtk_wrapper build issue reported in #30
Merge branch 'master' of git://github.com/JuliaLang/Tk.jl
Almost fixes Mac display issues (#30)

First window is fine, replot is upside down but flips when resized just a bit.

I still don't understand why the flip also has to occur each time in getView(), however.