Configurable Idle Timeout

The idle timeout can now be configured with -t timeOutInMS. The
default is now 4000 ms, down from 8000 ms. One rare bug that prevented
idle from working when no disk events arrive is fixed.
Rudimentary Help

When -h is passed, print a rudimentary help message and exit.
Merge commit 'a0cf42c2d5116e7245cb2128e4ccca585578bbd6'