MythTranscode should adjust streams when exporting to retain A/V sync

[darkstarsword@…]

When MythTranscode? is used to create fifos that will be used by other programs later it should optionally apply the same adjustments to the audio and video streams to keep corrupted streams in sync as mythtv applies when the recording is being played - dropping and/or adding frames as appropriate to either/both streams so that the syncronisation in the nuppelvideo format can be retained in other formats.

[stuartm]

Feature request without a patch.