Histogram2D and Histogram2DContour have wrong trace types

[kMutagene]

histogram2D -> histogram2d

Plotly.NET/src/Plotly.NET/Traces/Trace2D.fs

Lines 78 to 80 in 41e1e11

	///initializes a trace of type "histogram2D" applying the given trace styling function
	static member initHistogram2D (applyStyle: Trace2D -> Trace2D) =
	Trace2D("histogram2D") |> applyStyle

histogram2Dcontour -> histogram2dcontour

Plotly.NET/src/Plotly.NET/Traces/Trace2D.fs

Lines 82 to 84 in 41e1e11

	///initializes a trace of type "histogram2Dcontour" applying the given trace styling function
	static member initHistogram2DContour (applyStyle: Trace2D -> Trace2D) =
	Trace2D("histogram2Dcontour") |> applyStyle