Code Merge Request #1: Allow msqrt to accept multiple arguments (open)

If there is more than 1 argument, msqrt should treat all of its arguments as if they were in a single mrow. See http://www.w3.org/TR/MathML2/chapter3.html#i
d.3.1.3.1

P.S. If you prefer to receive patches some other way (e.g. ticket in addition to merge request, patch attached to ticket, etc.), please let me know.