- Make sure that the segments connecting the exon boxes are always drawn correctly
   by deriving the coordinates and the widths of the connecting segments from the precalculated coordinates
   and widths of the exon boxes
- Make sure that the right border of the last exon box does not extend beyond the total transcript width
   by using a custom interpolation function that always interpolates to the smallest integer
   rather than to the nearest one.

Co-authored-by: Imran Salam <imran@ebi.ac.uk>