gauge2_: Gauge2
In devOpifex/g2r: Interactive Grammar of Graphics

While gauge_() applies the scale to the global chart object, gauge2_() applies it to the view.

1	gauge2_(g, ..., fn)

`g`	An object of class `g2r` or `g2Proxy` as returned by `g2()` or `g2_proxy()`.
`...`	Arguments to customise the gauge. Generally, key value pairs of options, a vector of hex colors, or a JavaScript function (wrapped in `htmlwidgets::JS()`).
`fn`	Name of the function.