RoQ decoder: Remove misleading diagnostics.

It is not necessarily an error when a chunk does not cover a whole block.
Messages did not reflect the actual situation either.

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
RoQ-encoder: introducing Quake 3 compatibility option

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>