iplot('ratio') shoud sync X axis by default

[Binger-cn]

in a ratio diagram, when zoom in the lower 'ratio' part , the main diagram is not zoomed together, and vice versa. No param in iplot() can control this so far.

I think it's better synchronized by default.

[Binger-cn]

Found a makeshift: iplot('ratio', xrange=[minX, maxX] , ... )