RapydScript-NG fixes

[Bruce Sherwood]

A user reported that the RapydScript-NG Python-to-JavaScript transpiler treated

X = 5

X = -1 X**2

as though it were

X = 5

X = -1

X**2

and also treated

X = 5

X = (-X)**2

as though it were

X = 5

X = -(X**2)

Both of these bugs have been corrected by the RapydScript-NG developer, Kovid Goyal, who as usual responded to the report amazingly quickly. The fixed transpiler is now in use in GlowScript 2.6 VPython. Yay, Kovid!