Allowing imported graphics to be exposed as `pub mod`

[kouta-kun]

I would like imported graphics in a module to be (optionally) exposed as pub mod and be used from other modules than the one it was imported in.

I already have a POC of it in this fork but the README mentions that an issue should be opened first for discussion :)

[corwinkuiper]

To unblock, you can achieve this now using re-exports. For example:

pub mod bg {
   agb::include_background_gfx!(backgrounds, "FFFFFF", some_map => "some-data.aseprite");

   pub use backgrounds::*;
}

[gwilymk]

From the code it seems you do pub backgrounds in @corwinkuiper's example above? I think that makes perfect sense, so happy for you to PR that as well :).

[gwilymk]

Added in 0.21.0