This is a simple example of how to use threepp with WxWidgets.
As WxWidget is a complete GUI library, it is not necessary to use threepp's Canvas class. Instead, we can use WxWidgets'
wxGLCanvas and wxGLContext to create a window and a GL context, and then use threepp's GLRenderer to render to it.
Alas, the option THREEPP_WITH_GLFW should be set to OFF when building threepp.