Timing code should use hrtime() as opposed to microtime()

Various places in WissKI time things like this:

    $start = microtime(TRUE);
    // some code here
    $end = microtime(TRUE);
    $duration = $end - $start;

Microtime() returns wall clock time and is not guaranteed to be monotone.
From the documentation:

For performance measurements, using hrtime() is recommended.

We should update WissKI code accordingly.