Update pool copy cleanup

This small addition just makes sure that the .opensesame.pool temporary pool folder is cleaned up upon exit.
Bump to 2.9.0~pre30
Update android setup script
Bump to 2.9.0~pre31
Add PyGaze to modules() function
Change default sound_buf_size to 1024
- Avoids stuttering on Windows systems
Update debian/changelog
Bump to 2.9.0