Refactored project structure

- Test project is now separated from engine code
 - Engine code can now initialize OpenGL and GLUT correctly
 - Moved vectors and quaternions to a Math subdirectory

Fixed reorder warning

example/CMakeLists.txt

@@ -0,0 +1,19 @@
+add_executable(tests_opengl
+        main.cpp
+        displayers.h
+        displayers.cpp)
+
+target_link_directories(tests_opengl PRIVATE
+        ${PROJECT_SOURCE_DIR}/src)
+
+target_include_directories(tests_opengl PRIVATE
+        ${PROJECT_SOURCE_DIR}/src)
+
+target_link_libraries(tests_opengl
+        ${OPENGL_LIBRARIES}
+        ${GLUT_LIBRARIES}
+        engine)
+
+target_include_directories(tests_opengl PRIVATE
+        ${OPENGL_INCLUDE_DIR}
+        ${GLUT_INCLUDE_DIR})