Started moving SFML specific stuff into the sfml/ directory.

sfml/shaders.hpp

@@ -0,0 +1,27 @@
+#pragma once
+#include <cstdint>
+#include <vector>
+#include <string>
+#include <SFML/Graphics.hpp>
+#include <unordered_map>
+#include <memory>
+#include <nlohmann/json.hpp>
+
+namespace shaders {
+  struct Record {
+    std::string name;
+    std::string file_name;
+    std::shared_ptr<sf::Shader> ptr = nullptr;
+  };
+
+  struct ShaderManager {
+    std::unordered_map<std::string, Record> shaders;
+  };
+
+  std::shared_ptr<sf::Shader> get(const std::string& name);
+  void init();
+  bool load_shader(std::string& name, nlohmann::json& settings);
+  bool updated(int my_version);
+  int reload();
+  int version();
+}