Output of derived units

[fbruetting]

//Edit: As an extension to #54:

• I'm an electrical engineer and so it would be nice if all units could be convert to their electrical ones like V/A/F/H/W/C etc. This could maybe be altered to other scientific areas, where units should be interpreted in another form, like Å/m or J vs Nm, like in #54, or K/°C what would solve #8. So maybe there should be an option for a scientific area. This could be implemented as a global variable which is „common“ or „standard“ at first and displays the more common format, and can be altered e.g. by „electrical“, so that (just the therefore relevant) units are modified to fit that area.

• It also would be great, if the exponent of the unit could be modified, so that μV is used, instead of 1e-6 V. Maybe by implementing/respecting NumericIO somehow?

:)