Minor fix release.

Fixes

• Issue #37: improved accuracy of the MARK timer, optional, default: 20
  minutes. Generates log messages to files, which have had no activity
  within the MARK interval. Was off by up to interval / 2 minutes.
  It may now be off by up to 1 / 2 minutes, i.e.g, 30 seconds.
• Issue #64: sub-second faking of kernel timestamps was always zero