For content that is identified as likely to contain some
animation or graphics content, increase the availability
of split modes for good quality speeds 1-3.

On a problem test animation clip this improves metrics
results by about 0.25 db and makes a noticeable difference
visually. It also causes a small drop in file size (~0.5%) but
a rise in encode time of about 5-6% at speed  2.

For more normal content it should have no effect.

Change-Id: Ic4cd9a8de065af9f9402f4477a17442aebf0e439