truncatingFileWriter issues

[ronnno]

Several issues with truncatingFileWriter make it problematic in production environments:

1. does not support size based truncation
2. time from last truncation is initialized to the system clock on startup - so we never truncate if all runs are short
3. loosing recent log data at the time of truncation - no file rolling
4. Recovery from err on Truncate is wrong. in this case the object should probably return an error and just ignore the new "write".
   Instead, seek(0,0) only creates corrupt data, and is not checked for error in itself.