Function gl::load_with

pub fn load_with<F>(loadfn: F) where F: FnMut(&str) -> *const c_void

Load each OpenGL symbol using a custom load function. This allows for the use of functions like glfwGetProcAddress or SDL_GL_GetProcAddress. ~~~ignore gl::load_with(|s| glfw.get_proc_address(s)); ~~~