Function gfx_gtk::load_with

pub fn load_with<F>(get_proc_addr: F) where
    F: Fn(&str) -> *const c_void, 

Loads the Gl function pointers via epoxy, using the given lookup function, after initializing epoxy itself.

Functions names are looked up first in the current .exe, and, failing that, in the libepoxy dylib - attempting to load libepoxy-0, libepoxy0 and libepoxy

get_proc_addr must be a wrapper of epoxy::get_proc_addr()

Only use this function to provide your own wrapper. For "normal" use, load() or debug_load() are recommended instead