add colored_vertices shader for testing

src/main.cpp

@@ -343,12 +343,22 @@ main()
 				"../data/shader.frag",
 				"default"))
 		{
-			std::cout << "error loading shader program\n";
+			LOG(Error) << "error loading shaders\n";
+			return 1;
+		}
+
+		if (!addShaderProgram(arena,
+				rs->gl_ctx,
+				"../data/colored_vertices.vert",
+				"../data/colored_vertices.frag",
+				"colored_vertices"))
+		{
+			LOG(Error) << "error loading shaders\n";
 			return 1;
 		}
 
 		if (!loadScene(rs)) {
-			std::cout << "error loading scene\n";
+			LOG(Error) << "error loading scene\n";
 			return 1;
 		}