Use colorblind safe colours for ellipses

[sje30]

Hi,

Thanks for this tool; I'm using it to write a tutorial. Would you consider swapping the colours for the ellipses of each file? At the moment they are green/red. This is not a good choice for colorblind readers. A better default (and perhaps softer) might be to take some colours from the palettes available at: https://colorbrewer2.org/#type=qualitative&scheme=Set2&n=3

e.g. I've changed my local copy make2graph L375 to:

                (t->must_remake?"#fc8d62":"#66c2a5") /* https://colorbrewer2.org/#type=qualitative&scheme=Set2&n=3 */

Best wishes, stephen

[lindenb]

close afer https://github.com/lindenb/makefile2graph/pull/24