Also fixes some plot bugs with arcs.
Also moves polygonization of arcs (when required) in plotting code
from 5 degrees to calculated based on ARC_HIGH_DEF.
Fixes https://gitlab.com/kicad/code/kicad/issues/5017
Use 4 digits in mantissa as default and when exporting SVG.
Allow 0 as line width: this is the right value to draw filled shapes with no outline thickness.
ADDED arc, circle and rectangle shapes for schematic. Shapes support
line styles and fill colors.
CHANGED sheet background color in Edit Text & Graphics Properties to
fill color (and it now affects shapes).
Pushed STROKE_PARAMS down into common and moved all shapes to using it
for stroke descriptions.
Jeff Young
jean-pierre charras
Mark Roszko
Wayne Stambaugh