Port to OpenGL ES 2.0

Signed-off-by: Claudio Matsuoka <cmatsuoka@gmail.com>
Draw dots as circles instead of triangles

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

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