pyILPER 1.7.1 production

[rprosperi]

With a little help from Sylvain, I finally was able to explore a bit with the 7470A Plotter simulator, running one of the HP-75 Graphics Solutions Books programs which draws Line Charts.

For folks wondering about the nature of the pyILPer plotter simulator, I built a little graphic using the HP-75 program, 'printed' it to the plotter virtual device, and then saved it as a PDF. The file is attached below.

@Joachim - I did not encounter any issues, but I hardly did any testing... in fact I hardly did any using at all, but I wanted to report that the plotter device and PDF output option both behaved just as expected.