Unit conversion system

When checking the new tools implemented by our partners, I realised that the unit conversion system was not used in a consistent way by different tools. The e-Laboratory support team should discuss and agree on a one-fits-all unit conversion system.

As a reminder and base to start this discussion, here is how I initially designed the unit conversion system:

• Unit change applies to all field of that dimension. In one tool, the user cannot chose m for one length field and ft for another one.
• Only the unit for basic dimensions can be changed. So the user can change m for ft for instance, and this will automatically also change m/s to ft/s. This also means that user can't directly change m/s to ft/s, he has to change m to ft, which will of course be applied to lengths too. This allows to limit the number of units to chose and have some consistency, but I realise that it might not work for all cases.
• The user does not chose the prefix for units, this is done automatically by the unit conversion library (mathjs). So the user cannot chose mm for example, the library will automatically prefix m with mm, or cm, or km... depending on the value. This way, if for the same tool we have a field that is a small length and another one that is a big length, the small one could be displayed in mm and the big one in m.

I do not have the full list of members of the support team, so I am including only the ones which I know for sure are members of the team. @shentsov can you please include the missing ones?