Add support for clang

Signed-off-by: Jiří Župka <jzupka@gmail.com>
limit count of threads for loading images.

Leave some free cpu for opengl thread

Signed-off-by: Jiří Župka <jzupka@gmail.com>
Makes animation more smooth.

Signed-off-by: Jiří Župka <jzupka@gmail.com>
Increases cache size and adds supported video format.

Signed-off-by: Jiří Župka <jzupka@gmail.com>