Bug Fix for Stack with direction='in'

[gauriachalare123]

There is no way to specify max. no of layers for stack. If there are too many overlapping regions and when we specify stack direction = 'in' or 'center' the stack layers are getting plotted outside the specified the inner and outer radius. But in case of direction ='out' the layers are getting hidden . Layers are not getting plotted outside the specified inner and outer radius in case direction = 'out'.
Please refer issue #81

Change in Stack.js

if (this.conf.direction === 'in') {
return [
Math.max(this.conf.outerRadius - radialEnd, this.conf.innerRadius),
Math.max(this.conf.outerRadius - radialStart,this.conf.innerRadius)

  ]
}