Add missing input event listener.
Add unit test for `OpenGLWindow`.
Activate automoc only for `Graphics_Test_Common` library.
Revert "Activate automoc only for `Graphics_Test_Common` library."

This reverts commit 5525f852b3e793e6dc840808d75b3dfd30e5f3de.
Remove line break in `CMakeLists.txt`.
Merge remote-tracking branch 'origin' into maint-add-unit-test-for-opengl-window
Merge pull request #60 from DO-CV/maint-add-unit-test-for-opengl-window

[MAINT] Add unit test for `OpenGLWindow`.