Upstream improvement in svg_to_path.py

[NGExplorer]

There are some improvements in svg_to_paths.py which we want to upstream.

1. ellipse2pathd
   Use 'cubic' curve to draw ellipse/circle. 'arc' is not supported on all platforms.

2. polyline2pathd

   • Handle case of redundant 'z' command in polyline
   • Handle case when ellipse, polyline, rect does not have all attributes.
   • Add spaces between draw commands and its parameters

[NGExplorer]

Hello @mathandy ,
There is some improvement we've done in svg_to_paths.py and want to upstream our changes.
Is there some specific test-suite/procedure we need to follow before creating a pull request ?