function GridHelper(size, spacing, color)
{
	this.size = size !== undefined ? size : 100;
	this.spacing = spacing !== undefined ? spacing : 1;

	LineSegments.call(this, new BufferGeometry(), new LineBasicMaterial(
		{
			color: color !== undefined ? color : 0x888888,
			depthWrite: false,
			transparent: true,
			opacity: 0.5
		}));

	this.update();
}
Grid helper is used to visualize a grid in the editor.

Size, spacing and color of the grid can be costumized.

@class GridHelper
@param size {number} Total size of the grid.
@param spacing {number} Spacing between lines.
@param color {number} Hex color of the grid lines.