Fix filters output with adaptive driver

This is a small change I forgot to make when introducing DriverAdaptive. Basically, in this case the filters writing text files need to append the file, since otherwise only the last run in the adaptive procedure would be obtained.

I changed the behaviour only when using the adaptive driver, to avoid causing confusion in other cases. However, this could also be used to facilitate restarting from the same directory (although in this case it would be desirable to edit the existing file to keep only times before the restart).