outer legends for gr and pyplot and guide/margin improvements for gr

[daschw]

This implements the following legend positions for GR and PyPlot: :outertopleft, :outertop, :outerright, :outerleft, :outerbottomright, :outerbottomleft, :outerbottom

GR:

plot(rand(10), legend = :outertopleft)

plot(rand(10), legend = :outerbottom)

PyPlot

plot(rand(10), legend = :outerright)

plot(rand(10), legend = :outertop)

I don't want to show all possibilities here. In GR axes mirroring is respected for outer legend positioning as well. PyPlot needs some improvements for axes mirroring in general.

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Furthermore, this PR provides some improvemnets for guide positioning and margins in GR:

plot(100000rand(10), xformatter = x -> "my ticklabel $x", xrotation = 35, xlabel = "my x guide", yguide = "my y guide")

Old

New

plot(rand(10), xguide = "my x guide", yguide = "my y guide", margin = 10mm)

Old

New

plot(rand(10), title = "My big title", titlefont = font(30))

Old

New

[daschw]

Apparently I still have to update the reference images.

[blas-ko]

Amazing! This was just what I was (desesperately) looking for!
Thank you :)

[PowerUp77137]

how move legend for plotly() or plotlyjs() backend?