add symbolOffet as a pattern option, for a relative pixel offset to apply to symbols

[rmaceissoft]

add symbolOffet as a pattern option, for a relative pixel offset to apply to symbols, in case we don't want them overlapping the path.

Exampleof usage (symbolOffset=15)

Code:

var polyline = L.polyline(geometry, styles).addTo(map);
var decorator = L.polylineDecorator(polyline, {
  patterns: [
    {offset: 0, repeat: 200, symbolOffset: 15, symbol: L.Symbol.arrowHead({
      polygon: false,
      headAngle: 40,
      pixelSize: 10,
      pathOptions: {opacity: 1, weight: 2, stroke: true, color:'#2461AA'}
    })}
  ]
});

Screenshot: