byte_to_symbol was broken because it didn't iterate by byte, it
iterated by rust-char, which is a codepoint.
So it failed for everything outside of ascii and, because of a
mistaken bound, ascii chars from 0x21 to 0x2F ("!" to "/" - all the punctuation).
char_to_symbol will print printable codepoints as-is and
others escaped. This is okay - something like `decoded from: +` or
`decoded from: ö` is entirely understandable, there is no need to tell
you that "ö" is \xc3\xb6.
This reverts commit 423e5f6c039212fdd5d6b6f46e644666a460d944.
357eb3cd32