Support UTF normalization

[phochste]

Convert ä as represented by a + ¨ characters' code bytes: [61 cc 88] to UTF-8 character bytes: [c3 a4]

Hint:

 $ uconv -x any-nfc [catmandu output file] > [normalized file]

[jorol]

There are several characters which could be encoded as precomposed characters or as combining characters. You can use Unicode::Normalize for normalization:

use Unicode::Normalize;

my $nfc = NFC($nfd);

But I recommend to handle this outside of Catmandu with uconv because it's faster for big files:

$ uconv -x any-nfc camel_nfd.mrc | catmandu convert MARC to JSON > camel_nfc.json