Logging - Improved handling of partial writes in buffer

Improves handling of "partial-writes" in log-files. This occurred when many logfiles are simultaneously written to a nfs-mounted drive.

Bug Fixes

• [io]:
  • LogFileBase::writeCurrentLogStreamToFile() -> now does not raise an error when only parts (or none) of the requested bytes in the stream could be written. Instead these bytes remain in the buffer, thus the Logger tries to write them at its next execution cycle.