Add SI-derived units of Bar

[nielstron]

Is your feature request related to a problem? Please describe.
A number of SI-derived versions of Bar, even featured on the wikipedia page are missing.

Describe the solution you'd like
They may be added by a few simple lines noting all usual SI-derived versions (Mega, kilo,...)

Additional context
Causes another edge case for #161 (#162), resulting issues should be resolved