RArc::splitAt() works wrong in some cases.
To reproduce execute this script:

            var arc = new RArc(new RVector(0, 0), 100, Math.PI*2, Math.PI/2, true);
            var points = [];
            points.push(arc.getPointAtPercent(1/3));
            var arcs = arc.splitAt(points);
            if (arcs.length == 2) {
                qDebug("OK, arcs count:", arcs.length);
            } else {
                qDebug("FAILED, arcs count:", arcs.length);
            }

            arc.mirror(new RLine(0, 0, 0, 100));

            points = [];
            points.push(arc.getPointAtPercent(1/3));
            arcs = arc.splitAt(points);
            if (arcs.length == 2) {
                qDebug("OK, arcs count:", arcs.length);
            } else {
                qDebug("FAILED, arcs count:", arcs.length);
            }

The first case split in two arcs, but the second splits in one arc only.

I think the reason is the code in RArc::splitAt():

        ...
        if (RMath::getAngleDifference180(a1, a2))*radius()<0.001) {
            continue;
        }
        ...

The RMath::getAngleDifference180() return angle between -pi and pi so absolute value should be used.