#300 fast return for SegmentedTimeline.getExceptionSegmentCount()

[Adrian Nistor]

Method
"getExceptionSegmentCount(long fromMillisecond, long toMillisecond)"
in class SegmentedTimeline already has a fast return option:

if (toMillisecond < fromMillisecond) {
return (0);
}

but this is not all. This patch adds fast return when the
[fromMillisecond, toMillisecond] interval is before or after the first
or last exception segment respectively.

[Adrian Nistor]

fast return for SegmentedTimeline.getExceptionSegmentCount()