More code to deal with the flakey streams from NZ TV. They like to change the PCR...

More code to deal with the flakey streams from NZ TV. They like to change the PCR without sending a new PCR and we get big timestamp changes but no new reference clock. So now we look at the PTS and if its change is outside a tolerance window we use the new PTS as a PCR & declare a clock discontinuity.

git-svn-id: svn://localhost/HandBrake/trunk@2008 b64f7644-9d1e-0410-96f1-a4d463321fa5