proteins-to-viruses.py can generate a viral panel whose image is too large

[terrycojones]

A rather large viral panel, of 1929 viruses (and 269 samples) fails:

(35) biocloud ~/scratch/projects/sofia/pipelines/initial $ find . -name summary-proteins | proteins-to-viruses.py --html  --virusPanelFilename viral-sample-read-counts.png --sampleNameRegex '^\./(\d+-\d+)/' > index.h>
Traceback (most recent call last):
  File "/scratch/tcj25/root/.virtualenvs/35/bin/proteins-to-viruses.py", line 108, in <module>
    sampleTotalReadCountFilename=args.sampleTotalReadCountFilename))
  File "/scratch/tcj25/root/.virtualenvs/35/lib/python3.5/site-packages/dark/proteins.py", line 319, in toHTML
    self.virusPanel(virusPanelFilename, sampleTotalReadCountFilename)
  File "/scratch/tcj25/root/.virtualenvs/35/lib/python3.5/site-packages/dark/proteins.py", line 735, in virusPanel
    figure.savefig(filename)
  File "/scratch/tcj25/root/.virtualenvs/35/lib/python3.5/site-packages/matplotlib/figure.py", line 1563, in savefig
    self.canvas.print_figure(*args, **kwargs)
  File "/scratch/tcj25/root/.virtualenvs/35/lib/python3.5/site-packages/matplotlib/backend_bases.py", line 2232, in print_figure
    **kwargs)
  File "/scratch/tcj25/root/.virtualenvs/35/lib/python3.5/site-packages/matplotlib/backends/backend_agg.py", line 527, in print_png
    FigureCanvasAgg.draw(self)
  File "/scratch/tcj25/root/.virtualenvs/35/lib/python3.5/site-packages/matplotlib/backends/backend_agg.py", line 469, in draw
    self.renderer = self.get_renderer(cleared=True)
  File "/scratch/tcj25/root/.virtualenvs/35/lib/python3.5/site-packages/matplotlib/backends/backend_agg.py", line 486, in get_renderer
    self.renderer = RendererAgg(w, h, self.figure.dpi)
  File "/scratch/tcj25/root/.virtualenvs/35/lib/python3.5/site-packages/matplotlib/backends/backend_agg.py", line 93, in __init__
    self._renderer = _RendererAgg(int(width), int(height), dpi, debug=False)
ValueError: Image size of 2500x77200 pixels is too large. It must be less than 2^16 in each direction.