message texture cache + message image loader (no inline images yet)

src/message_image_loader.hpp

@@ -0,0 +1,27 @@
+#pragma once
+
+#include <solanaceae/message3/registry_message_model.hpp>
+
+#include "./image_loader.hpp"
+#include "./texture_cache.hpp"
+
+#include <optional>
+
+class MessageImageLoader {
+	std::vector<std::unique_ptr<ImageLoaderI>> _image_loaders;
+
+	public:
+		MessageImageLoader(void);
+		std::optional<TextureEntry> load(TextureUploaderI& tu, Message3Handle c);
+};
+
+// TODO: move to rmm
+template<>
+struct std::hash<Message3Handle> {
+	std::size_t operator()(Message3Handle const& m) const noexcept {
+		const std::size_t h1 = reinterpret_cast<std::size_t>(m.registry());
+		const std::size_t h2 = entt::to_integral(m.entity());
+		return (h1 << 3) ^ (h2 * 11400714819323198485llu);
+	}
+};
+