Add "How to get a transparent background" page

[jkrumbiegel]

I think the docs.makie.org/stable/how-to/do-something is a good url pattern, in the how-tos we can add all sorts of little cook-book style things without much explanation.

[MakieBot]

Compile Times benchmark

Note, that these numbers may fluctuate on the CI servers, so take them with a grain of salt. All benchmark results are based on the mean time and negative percent mean faster than the base branch. Note, that GLMakie + WGLMakie run on an emulated GPU, so the runtime benchmark is much slower. Results are from running:

using_time = @ctime using Backend
# Compile time
create_time = @ctime fig = scatter(1:4; color=1:4, colormap=:turbo, markersize=20, visible=true)
display_time = @ctime Makie.colorbuffer(display(fig))
# Runtime
create_time = @benchmark fig = scatter(1:4; color=1:4, colormap=:turbo, markersize=20, visible=true)
display_time = @benchmark Makie.colorbuffer(display(fig))

	using	create	display	create	display
GLMakie	10.92s (10.75, 11.10) 0.15+-	1.11s (1.09, 1.19) 0.04+-	782.80ms (768.75, 836.17) 24.24+-	9.44ms (9.27, 9.55) 0.11+-	135.81ms (133.02, 142.06) 3.30+-
master	10.95s (10.81, 11.12) 0.11+-	1.10s (1.07, 1.14) 0.02+-	788.28ms (765.24, 809.52) 15.39+-	9.51ms (9.26, 9.70) 0.17+-	135.85ms (132.59, 139.70) 2.52+-
evaluation	-0.34%, -0.04s invariant (-0.28d, 0.62p, 0.13std)	+1.49%, 0.02s invariant (0.54d, 0.34p, 0.03std)	-0.70%, -5.48ms invariant (-0.27d, 0.62p, 19.81std)	-0.78%, -0.07ms invariant (-0.51d, 0.36p, 0.14std)	-0.03%, -0.05ms invariant (-0.02d, 0.98p, 2.91std)
CairoMakie	10.07s (9.97, 10.14) 0.07+-	1.11s (1.09, 1.12) 0.01+-	213.20ms (209.87, 217.66) 2.82+-	9.55ms (9.49, 9.62) 0.05+-	5.73ms (5.64, 5.81) 0.06+-
master	10.03s (9.98, 10.08) 0.04+-	1.10s (1.10, 1.12) 0.01+-	213.14ms (210.14, 216.93) 2.48+-	9.61ms (9.46, 9.76) 0.12+-	5.77ms (5.69, 5.85) 0.06+-
evaluation	+0.31%, 0.03s invariant (0.58d, 0.30p, 0.05std)	+0.06%, 0.0s invariant (0.07d, 0.89p, 0.01std)	+0.03%, 0.06ms invariant (0.02d, 0.97p, 2.65std)	-0.61%, -0.06ms invariant (-0.64d, 0.26p, 0.08std)	-0.69%, -0.04ms invariant (-0.64d, 0.25p, 0.06std)
WGLMakie	14.12s (14.08, 14.17) 0.04+-	1.34s (1.33, 1.37) 0.01+-	12.43s (12.27, 12.59) 0.11+-	15.93ms (15.00, 17.11) 0.72+-	1.14s (1.06, 1.23) 0.05+-
master	14.11s (14.07, 14.16) 0.03+-	1.33s (1.26, 1.36) 0.03+-	12.40s (12.25, 12.55) 0.11+-	16.05ms (14.96, 17.01) 0.78+-	1.16s (1.13, 1.19) 0.02+-
evaluation	+0.10%, 0.01s invariant (0.38d, 0.49p, 0.04std)	+1.00%, 0.01s invariant (0.51d, 0.36p, 0.02std)	+0.26%, 0.03s invariant (0.29d, 0.60p, 0.11std)	-0.79%, -0.13ms invariant (-0.17d, 0.76p, 0.75std)	-1.16%, -0.01s invariant (-0.32d, 0.56p, 0.04std)