add speed up demonstration of datashader

[Sonja-Stockhaus]

Little benchmark to demonstrate in which cases it is helpful to use datashader to increase rendering speed

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[LucaMarconato]

Thanks for the PR, this is very informative! Just a few minor comments:

• I'd remove the variables mpl_sds and ds_sds as they are not used (also, maybe you have already seen, the developers don't recommend to compute these statistics https://docs.python.org/3/library/timeit.html#timeit.Timer.repeat).
• The empirical indication that for ~1000 polygons on datashader is faster is very useful! Could you please also add a section to check this for points and circles?

Thanks a lot!

[LucaMarconato]

• Regarding the failing docs, it seems that it can be fixed by using this myst configuration setting: WARNING reference target not found, even though reference exists executablebooks/MyST-Parser#519 (comment), in conf.py.

[timtreis]

• Regarding the failing docs, it seems that it can be fixed by using this myst configuration setting: WARNING reference target not found, even though reference exists executablebooks/MyST-Parser#519 (comment), in conf.py.

We actually already seem to have that. Will try to remove the HTML logic

[timtreis]

@Sonja-Stockhaus @LucaMarconato I fixed some things that were causing warnings in other notebooks. Apparently, this fixed it.

[timtreis]

@Sonja-Stockhaus I modified your notebook slightly to have less redundant code. For testing I reduced the number of points. Will rerun over-night with enough Points to see the effect.

However, for merging I'd wait until your main PR is merged because I want these to be real version accessible from PyPi.

[LucaMarconato]

@timtreis ready to merge??

[timtreis]

Not yet. On the one hand is datashader not faster for points, so that's weird. And then I wanted to first release sonjas feature branch so that the watermark has an actual release version attached and not a GitHub commit