javalib Zip methods need to be able to read & write UTF-8 names and comments.

[LeeTibbert]

This is a duplicate of PR #937 opened August 15, 2017.

The code is clearly marked as TODO: add correct UTF-8 support.

From tracing so far:

• it looks like one must be careful to check .zip both a zip file written on Window and one written on
  unix-like. The name & comment encodings may differ.

• it looks like the SN java.util.zip code makes some attempt to handle two and three byte UTF-8
  but not four byte. The code was probably written well before Java handled 4 byte UTF-8.

  I suggest replacing that code with the current practice of using a StandardCharsets.UTF_8 when
  the zip general purpose flag indicates UTF-8 output for names & comments.

• Current practice in the SN code seems to be to always write UTF-8, even if the general purpose flag
  is clear, indicating MS-DOS CP 437 should be used. Since CP 437 is also single byte, the practice, in some places,
  in the code of using Latin-1 iso-8859-1 should give byte compatible output, without the possibility of
  tripping over Unicode Surrogates, pairs of CP 437 can even express such.

  The use of Latin-1 is a bit of slight-of-hand which should be commented in the file. Exceedingly hard
  to trace and convince oneself that it is correct. A good exam or job-interview question for those
  who thrive on CharSets. CP 437 is not one of the standard Java CharSets. The slight-of-hand
  binary passthrough avoids some poor, benighted SN devo having to implement a custom
  CharSet provider for it.

---

Sometime in 2006 or so, the info-zip specification was updated to allow UTF-8 file names and comments.

Currently java.util.zip are, unconditionally, reading & writing something akin to Latin-1. Java uses UFT-16
for characters, which is a superset of Latin-1. That means that there are names and comments which
can be expressed in Java but not in java.util.zip.

Where this may beecome more than a theoretical gee-whiz concern is with efforts to implement the jdk.zipfs
file system.