Macro resources 

macro_rules! resources {
    () => { ... };
}

Surface the resources day-build generated for this crate as pub mod res (§18.5).

day::resources!();   // then: res::str::app_title(), res::images::logo, res::locales::CATALOG

Expands to the include! of $OUT_DIR/day_resources.rs, so the crate needs the day-build build script that writes it; an app with no build.rs has no OUT_DIR and should not call this. Kept separate from day_start! because entry points are per-target cfg, while res has to exist on every build, including the desktop one whose entry is src/main.rs.