BlPolygonGeometry should take corner radius into account

[plantec]

This would allow very nice rendering as selection in the sublime text editor.

[tinchodias]

Interesting. As a reference: The Roassal3 polygon supports it (See RSPolygon>>cornerRadii:). A method comment links to https://riptutorial.com/html5-canvas/example/18766/render-a-rounded-polygon-

[tinchodias]

The the record... hit testing bug in RS3: https://github.com/pharo-graphics/Roassal/issues/62

[tinchodias]

Some related information in the web:

• https://observablehq.com/@daformat/rounding-polygon-corners
• https://www.gorillasun.de/blog/an-algorithm-for-polygons-with-rounded-corners/
• https://stackoverflow.com/questions/24771828/how-to-calculate-rounded-corners-for-a-polygon