Include error code in .toString representation of RuntimeError
Include error code in .toString representation of RuntimeError

aaronmars/vexflow,Silverwolf90/vexflow,Huji/vexflow,Huji/vexflow,Huji/vexflow,Tails/vexflow,Tails/vexflow,aaronmars/vexflow,Silverwolf90/vexflow,Tails/vexflow,aaronmars/vexflow,Silverwolf90/vexflow