Refactor renderer and input handling; add OBJ loader and math utilities

- Updated renderer.h to replace Vec3 and Vec2 structs with Math namespace equivalents.
- Introduced Texture struct to manage texture properties.
- Modified Triangle struct to use Texture instead of GLuint for texture handling.
- Removed deprecated matrix functions and replaced them with Math namespace methods.
- Implemented InputManager class for better input handling, including key and mouse state tracking.
- Added ObjLoader class to load OBJ files and associated textures, with MTL file parsing.
- Created math utilities for fixed-point arithmetic and vector/matrix operations.
- Added time management class for frame timing and delta time calculations.

Engine/loader/obj_loader.h

@@ -0,0 +1,15 @@
+#ifndef OBJ_LOADER_H
+#define OBJ_LOADER_H
+
+#include "renderer.h"
+#include <string>
+#include <vector>
+
+class ObjLoader
+{
+public:
+    static std::vector<Triangle> load_obj(const std::string& obj_filepath, 
+                                        Renderer& renderer);
+};
+
+#endif