How to print large graphs across multiple pages (23 Feb 2017).
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The graphviz dot format has a 'page' section that can apparently split a graph
over pages, but it's not well documented and difficult to use (it requires
dimension in inches etc., not simply page and array size such as '3x3 A4').

pdfposter: get latest version from github.  The official one in Ubuntu
generates blank pages.  This can generate a multi-page pdf.  Unfortunately the
evince viewer doesn't seem to be able to print them properly - some page edges
get cropped.

Adobe Reader on Windows can print a single-page PDF over multiple pages. This
works well.
