This uses a box shape for the sequence headers; they take up less
horizontal space than ovals which allows the image to be larger.
This also adjusts the edges so that the virtal lines are straight.
More newlines are used in order to further shrink the horizontal
space (and produce a more square aspect ratio for better legibility).
The note is horizontally compressed and moved to be closer to both
edges that it references.
Change-Id: Ib0d403d4f94ea06c86fdc1a6d7d02970b7f9961f
ef50c4f93c