Adding textures capabilities

* Added Texures to the two sample cubes
* Modified mesh structure
	- mesh now contains indices and vertices
	- Vertices contain vertices and uv's (later on they will also
	contain normals)

Solution definitely not perfect and needs improvement.

SandboxApplication/GUI.cpp

@@ -32,4 +32,10 @@ void transformWindow(Transform& transform, std::string PanelName) {
     ImGui::InputFloat3("Scale:", (float*)&transform.Scale[0]);
     ImGui::End();
 
+}
+
+void materialWindow(Material& material, std::string PanelName) {
+    ImGui::Begin(PanelName.c_str());
+    ImGui::ColorPicker3("Color:", &material.Color[0]);
+    ImGui::End();
 }