Changed determinination of intermediate arrival/departure times such
that they always differ by at least 1 msec. This way they show up in
proper order when using a db query.
Fixed filteredList() to properly return fraction as a double when
dividing two integers.
Improved some comments. No functional changes.
Fixed typo in a logging message. No functional changes.
Wasn't handling headwaySecs properly for blocks when using frequencies
to describe assignments.