newRPL: Handling of units

[Claudio L.]

Fantastic review of units. Thank you for that, as it was hard for me to find updated information on some units.
I'll go over each and every one of your points and make sure they are taking care of. Bugs first, suggestions later.
Some units were outdated and I applied a more modern definition, but still I wasn't trying to depart too much from the 50g names because of compatibility with existing code.
But I'm up for a more modern set of units, so I'll do a thorough review based on your post.