Warning: Call-time pass-by-reference has been deprecated

With PHP version 5.2.6 the following message appears twice at the top of the page, and the timeline is blank:

Warning: Call-time pass-by-reference has been deprecated; If you would like to pass it by reference, modify the declaration of [runtime function name](). If you would like to enable call-time pass-by-reference, you can set allow_call_time_pass_reference to true in your INI file in .../sites/all/modules/timeline/classes/Timeline.class.inc on line 84

Rather than enabling call-time pass-by-reference, I did this:

Removed the & from the two arguments on line 84 of Timeline.class.inc, and added them into line 24 of TimelineEvent.class.inc.