Modified CMake to now find and link GLEW

Slight tweaks to how CMake interacts with VS
Added small OpenGL testing class which draws over the raycasted image
Going to use Gl to start helping with debug / enabling hybrid rendering

include/util.hpp

@@ -10,7 +10,6 @@ const double PI = 3.141592653589793238463;
 const float  PI_F = 3.14159265358979f;
 
 struct Light {
-#pragma pack(1)
 	sf::Vector4f rgbi;
 
 	// I believe that Vector3's get padded to Vector4's. Give them a non-garbage value
@@ -163,7 +162,7 @@ inline std::string read_file(std::string file_name){
 
 	if (!input_file.is_open()){
 		std::cout << file_name << " could not be opened" << std::endl;
-		return nullptr;
+		return "";
 	}
 
 	std::stringstream buf;