Re: [boost] units: review

I forgot one additional comment... for clarity, I would recommend eliminating the duplicate unit names (SI::meter, SI::meters, SI::metre, SI::metres, etc). For one thing, to maintain consistency, users might then feel obligated to do this in their own unit systems as well. I think it makes more sense to just pick a convention and stick with it, especially for the singular vs plural, which is really just a matter of taste, and users will learn to deal with whichever one the library writers pick :-). As for the alternate spellings, I guess if that's a political issue they could stay, but the plurals definitely seem gratuitous to me. -Lewis