Issue title: Problem with rendering \Omega for SI-unit Ohm
 Issue body: Hey everbody! :-)

I am trying to use Jupyter-Notebooks for creating engineering calculation sheets.
Therefore i found handcalcs and forallpeople packages for SI-uinit support.

Works quite nice, but I have trouble with rendering \Omega for Ohm:
![Screenshot from 2021-01-30 17-32-38](https://user-images.githubusercontent.com/63588234/106362262-25413380-6322-11eb-8be6-c3da7e68d949.png)

Whats the matter here? Any Ideas?

Cheers!
 Comments: 
 Comment 0: Hi @tmrgr,

Thanks for posting the issue! I have an idea about what's going on here. Will try to get this patched ASAP. I think it's related to another problem.

Will let you know when it is
 Comment 1: I'm also seeing this where the omega is a derived unit:

![image](https://user-images.githubusercontent.com/82988/120563235-fdf99080-c3ff-11eb-94b7-b32cb81b920e.png)

 Comment 2: Hi all (@tmrgr, @psychemedia),

I have just patched this in a new version of `forallpeople` (that's where the problem was). You can upgrade to v. 2.0.1 of forallpeople as of now and it should be fixed.

Thanks for your patience!
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