Migrate to Gtk only?

[ararslan]

Currently this package uses Tk by default with the option of using Gtk. However, the Tk package does not support precompilation, which means Winston similarly cannot support it. If we make the switch to Gtk, we'll get precompilation plus faster rendering. See discussion in https://github.com/JuliaGraphics/Winston.jl/pull/279 for some further details. What are your thoughts? cc @nolta in particular.

[nolta]

I'm ok with switching, but it seem premature, given this problem.

[ararslan]

Right, it would take some updating and maintenance up front, likely both here and Gtk.

[tknopp]

ping @ararslan, I agree that this should be done. Should I prepare a PR?

[ararslan]

If you'd be willing to do that, I think it's the right way to go!