To compare screenshots, it is better to have
an image with no top and bottom black borders.

Signed-off-by: Geoffrey Métais <geoffrey.metais@gmail.com>

Signed-off-by: Geoffrey Métais <geoffrey.metais@gmail.com>

On some devices, without delay, the screenshot
takes an earlier and bad frame

Signed-off-by: Geoffrey Métais <geoffrey.metais@gmail.com>

Close #265

This reverts commit 26c7dab9.
It appears to break the build on some platforms & causes runtime issues
on some devices

Call attachToGLContext/detachFromGLContext on a same SurfaceTexture instance.
That way, we don't have to re-configure MediaCodec in order to setup the new
Surface when the video size change mid-stream (and when a new OpenGL vout is
created).