Shared datatypes for azul-* crates
azul-core provides the platform-independent core types used throughout
the Azul toolkit. Key modules include [dom] for DOM construction,
[callbacks] for event callback types, [styled_dom] for the CSSOM,
and [window] for OS windowing abstractions.
This crate depends on [azul_css] for CSS property definitions and is
consumed by azul-layout, azul-dll, and the platform shell crates.
It supports no_std environments via #![cfg_attr(not(feature = "std"), no_std)].