Implement zerror and surface type recipe fixes

[daschw]

using Plots

struct Measurement <: Number
    val::Float64
    err::Float64
end
value(m::Measurement) = m.val
uncertainty(m::Measurement) = m.err

@recipe function f(::Type{T}, m::T) where T <: AbstractArray{<:Measurement}
    if !(get(plotattributes, :seriestype, :path) in [:contour, :contourf, :contour3d, :heatmap, :surface, :wireframe, :image])
        error_sym = Symbol(plotattributes[:letter], :error)
        plotattributes[error_sym] = uncertainty.(m)
    end
    value.(m)
end

x = Measurement.(10sort(rand(10)), rand(10))
y = Measurement.(10sort(rand(10)), rand(10))
z = Measurement.(10sort(rand(10)), rand(10))
surf = Measurement.((1:10) .* (1:10)', rand(10,10))

plot(
    scatter(x, [x y], msw = 0),
    scatter(x, y, z, msw = 0),
    heatmap(x, y, surf),
    wireframe(x, y, surf),
    legend = :topleft
)

cc: @briochemc