#1720 Support Library of Congress LCCN normalization

[Ahasuerus]

According to https://lx2.loc.gov/#scrollNav-2 , the Library of Congress "normalizes" LCCNs when they are used in LOC permalinks. For example, LCCN "gm 71-2450" translates to https://lccn.loc.gov/gm71002450 by removing spaces and hyphens and padding the number after the hyphen with zeros.

We want to continue entering LCCNs as they appear in publications, i.e. including dashes and, where applicable, spaces. We need to modify our software to transparently generate "normalized" LCCN-based URLs to link to the correct online record on the LOC Web site. See the linked LOC Web page for the normalization algorithm.