Issue 291 highlighted  the fact that CQ mode was not working
as expected in 1 pass mode,

This commit fixes that specific problem but in so doing I also
uncovered an overflow issue in the VBR code for 1 pass and
some data values not being correctly initialized.

For some clips (particularly short clips), the resulting
improvement is dramatic.

Change-Id: Ieefd6c6e4776eb8f1b0550dbfdfb72f86b33c960