Fast blanked DVD-RW can only be burned in DAO mode. Some DVD drives
can't detect whether DVD-RW is fast or fully blanked, and the only
way to know it is from the error message from growisofs.

Currently k3b shows very uninformative message:
"Fatal error during recording: Input/output error".
This is because the output of growisofs is not parsed correctly.
First of all, stderr output is lost when growisofs is finished,
because K3b::ActivePipe closes the corresponding K3b::Process.
This is fixed by separating stderr and stdout channels of
growisofs. Secondly, the existing code assumes that the message
starts with ":-[", while it actually starts with ":-(".

Probably the bug was introduced 10 years ago by the commit
3f6bf50c23d7e44eb677ccd70aac0cb21550790f.