Plots.jl: Axis label (guide?) needs padding

[BioTurboNick]

The y-axis label (in GR) is too close to the axis tick labels, and there doesn't appear to be an attribute to modify this.

[steinQF]

The same issue exists in plotlyjs, at least for logarithmic scales (which have tick labels that are wider than usual).

[mkborregaard]

@jheinen could this be an artifact of https://github.com/JuliaPlots/Plots.jl/commit/61d13b9b2d783f2ffa8cebb2518843951c25f20e ?

[jheinen]

@mkborregaard : Yes, we need a solution that takes the effective/maximum length of the labels into account. Otherwise, we will always "waste space".

[mkborregaard]

I think wasting space is a lot better than overlap, though, if we have to choose. I think it should be possible to calculate the the labels from the ticks and tickfont, which are available in the plotattributes object at backend time.

[daschw]

I think that's fixed for GR in #2018:

using Plots
plot([0, 1], yguide = "p(chance association)")

I agree that PlotlyJS with scientific format could use a little more space.