Lays out the renderables in a single line. Taking into account
the following variables:
- true-size
- margins
- spacing
- justify
- center align
function _layoutLine(next, endReached) {
        if (!lineNodes.length) {
            return 0;
        }

        // Determine size of the line
        var i;
        var lineSize = [0, 0];
        var lineNode;
        for (i = 0; i < lineNodes.length; i++) {
            lineSize[direction] = Math.max(lineSize[direction], lineNodes[i].size[direction]);
            lineSize[lineDirection] += ((i > 0) ? spacing[lineDirection] : 0) + lineNodes[i].size[lineDirection];
        }

        // Layout nodes from left to right or top to bottom
        var justifyOffset = justify[lineDirection] ? ((lineLength - lineSize[lineDirection]) / (lineNodes.length * 2)) : 0;
        var lineOffset = (direction ? margins[3] : margins[0]) + justifyOffset;
        var scrollLength;
        for (i = 0; i < lineNodes.length; i++) {
            lineNode = lineNodes[i];
            var translate = [0, 0, 0];
            translate[lineDirection] = lineOffset;
            translate[direction] = next ? offset : (offset - (lineSize[direction]));
            scrollLength = 0;
            if (i === 0) {
                scrollLength = lineSize[direction];
                if (endReached && ((next && !alignment) || (!next && alignment))) {
                    scrollLength += direction ? (margins[0] + margins[2]) : (margins[3] + margins[1]);
                }
                else {
                    scrollLength += spacing[direction];
                }
            }
            lineNode.set = {
                size: lineNode.size,
                translate: translate,
                scrollLength: scrollLength
            };
            lineOffset += lineNode.size[lineDirection] + spacing[lineDirection] + (justifyOffset * 2);
        }

        // Set nodes
        for (i = 0; i < lineNodes.length; i++) {
            lineNode = next ? lineNodes[i] : lineNodes[(lineNodes.length - 1) - i];
            context.set(lineNode.node, lineNode.set);
        }

        // Prepare for next line
        lineNodes = [];
        return lineSize[direction] + spacing[direction];
    }