On slow machine, should not use CPU demosaic when paused

[Andrew Baldwin]

On some machines, CPU demosaic can take seconds per frame.

This makes interaction in pause mode very slow.

Should find a way to intelligently use high quality mode if machine is fast enough.

[Andrew Baldwin]

Fixed by 9338749378178d0f03998803e5039bf6e3b4cdb7

We now measure the average time it takes for CPU demosaicing

It is only used in pause mode if it averages under half a second.

[Andrew Baldwin]

Fixed in 9338749378178d0f03998803e5039bf6e3b4cdb7