The LinePositionComparator is optionally called by text extraction algorithms
to help insure text lines found on a page are ordered using the y coordinates
of the bounding box in the cartesian plane's fourth quadrant. The sorting
tries to order the line blocks via the coordinate system rather then the order
that they were plotted in.
It's assumed that all LineText that is a child of PageText will not be
sorted on the x access. The class WordPositionComparator will be used
to insure that words are ordered correctly in the parent PageText array.