Add Asset system

- Add Abstract Asset class which defines Assets
- Add AssetManager class to keep track of all the Asset
- Add AssetFile class to cache the asset without loading it
- Add UUID class to uniquely identify assets
- Add MetaFile class to load meta asset files

CopiumEngine/src/copium/util/MetaFile.h

@@ -0,0 +1,56 @@
+#pragma once
+
+#include <iostream>
+#include <map>
+#include <string>
+#include <vector>
+
+namespace Copium
+{
+  class MetaFileClass
+  {
+    friend class MetaFile;
+    private:
+      std::map<std::string, std::string> values;
+
+    public:
+      MetaFileClass() {}
+      MetaFileClass(const std::map<std::string, std::string>& values)
+        : values{values}
+      {}
+      std::string GetValue(const std::string& key, const std::string& val) const;
+      bool HasValue(const std::string& key) const;
+      const std::string& GetValue(const std::string& key) const;
+      const std::map<std::string, std::string>& GetValues() const;
+
+      void AddValue(const std::string& key, const std::string& val);
+
+      friend std::ostream& operator<<(std::ostream& stream, const MetaFileClass& file);
+  };
+
+  class MetaFile
+  {
+    private:
+      std::string filepath;
+      std::map<std::string, MetaFileClass> classes; // map<class, map<variable, value>>
+
+    public:
+      MetaFile();
+      MetaFile(const std::string& filepath);
+      MetaFile(std::istream& stream);
+
+      bool HasMetaClass(const std::string& className) const;
+      MetaFileClass& GetMetaClass(const std::string& className);
+      const MetaFileClass& GetMetaClass(const std::string& className) const;
+      const std::string& GetFilePath()  const;
+
+      void AddMetaClass(const std::string& name, const MetaFileClass& metaClass);
+
+      friend std::ostream& operator<<(std::ostream& stream, const MetaFile& file);
+      friend std::istream& operator>>(std::istream& stream, MetaFile& file);
+
+      static std::vector<MetaFile> ReadList(const std::string& file);
+    private:
+      void LoadMetaFile(std::istream& stream);
+  };
+}