Add 3 new type of object: Sphere, Object and Intersect.

Add Intersect object as a way to report where a ray intersect another object and which one it is.
Add an Object base class for all object that can be rendered.
Add the Sphere object.

tests/CMakeLists.txt

@@ -3,7 +3,8 @@ project(DoRayTested)
 set(THREADS_PREFER_PTHREAD_FLAG ON)
 find_package(Threads REQUIRED)
 
-set(TESTS_SRC tuple_test.cpp colour_test.cpp canvas_test.cpp matrix_test.cpp transformation_test.cpp ray_test.cpp)
+set(TESTS_SRC tuple_test.cpp colour_test.cpp canvas_test.cpp matrix_test.cpp transformation_test.cpp ray_test.cpp
+        intersect_test.cpp sphere_test.cpp)
 
 add_executable(testMyRays)
 target_include_directories(testMyRays PUBLIC ${gtest_SOURCE_DIR}/include ${gtest_SOURCE_DIR})