Write a string in whichever form is shorter

[tannevaled]

A PDF string may be written between parentheses or in hex, and the writer only
knew the first. A literal string spells every unprintable byte as a
four-character octal escape, and text that is not Latin-1 is written in UTF-16
— so a string of ordinary prose in any other script came out four times its
own length. The hex form costs two characters a byte whatever the byte is, so
the writer now measures both and takes the shorter.

The corpus makes the case: one file carries a diagram's whole source in its
information dictionary, and rewriting it produced 3.7 MB from 1.2 MB, almost
all of it octal escapes. Across the whole corpus the rewrite drops from 98.9%
of the input to 98.8%, which is what a change that only bites on non-Latin
text looks like in an English-language corpus; on the file that motivated it,
the string itself halves.

All 118 833 files still rewrite to an identical fingerprint. Exact 100%
statement coverage, go vet clean.