Added 2D Vector structure

SDLU_Example/main.cpp

@@ -1,6 +1,11 @@
 #include "header.hpp"
 
+#include <iostream>
+
 int main(int argc, char** argv)
 {
+    sdlu::Vector2f vec(.4f, -2.3f);
+    std::cout << "Vector2f: " << vec.x << ", " << vec.y << std::endl;
+
     return 0;
 }