Improve hpgl import (doesn't support CI circle or other Circle, Arc, and Polygon commands)

Summary:

I expect that Inkscape could read *.Hpgl file but in the case of the Ci circle command nothing appear !

Steps to reproduce:

Open a HPGL file with Inkscape

What happened?

Nothing right ! this function is not know !

What should have happened?

Interprete the ci command in HPGL file to display one or more circles

IN;PU; SC 6822,17149,4235,14562; IP 6822,4235,17149,14562; PA20550,13748; CI3450PU; PA21684,12614; CI3450PU; PA22818,11480; CI3450PU; PA23952,10346; CI3450PU; PA25086,9212; CI3450PU; PA26220,8078; CI3450PU; PA27354,6944; CI3450PU; PU;PA0,0;