Merge pull request #38 from rsrock/master

RFC: Fix for Mac display issues
build with latest version of library on linux
Merge pull request #39 from rennis250/master

Build when linux user only has tk/tcl 8.6 installed
Build tk wrapper with -mmacosx-version-min=10.6
OS X option should only be run on :Darwin. Fix #41.
Remove the "pain and suffering" from the Mac side of tk_wrapper
Cleanup code for Mac
Allow binding popup menus to Canvas objects
Move flip to Cairo
Merge branch 'master' of git://github.com/JuliaLang/Tk.jl