staging some future refactoring, .h -> hpp, fix for rendering w/ audio

src/anm2/layer.hpp

@@ -0,0 +1,21 @@
+#pragma once
+
+#include <string>
+#include <tinyxml2/tinyxml2.h>
+
+namespace anm2ed::anm2
+{
+  class Layer
+  {
+  public:
+    std::string name{};
+    int spritesheetID{};
+
+    Layer() = default;
+    Layer(tinyxml2::XMLElement*, int&);
+    tinyxml2::XMLElement* to_element(tinyxml2::XMLDocument&, int);
+    void serialize(tinyxml2::XMLDocument&, tinyxml2::XMLElement*, int);
+    std::string to_string(int);
+    bool is_spritesheet_valid();
+  };
+}