Investigating non-transparent tetracube bug

Signed-off-by: Claudio Matsuoka <cmatsuoka@gmail.com>
Add workaround for glenz palette setting

Signed-off-by: Claudio Matsuoka <cmatsuoka@gmail.com>
Add texture fragment shader for glenz chessboard

Signed-off-by: Claudio Matsuoka <cmatsuoka@gmail.com>