Add another encoding

[Yen-Ju Chen]

  I want to ask whether GNUstep can add another encoding
  for Traditional Chinese in NSString.h, Unicode.m and other related files.
  The encoding for Traditional Chinese is "BIG5".
  So the encoding name could be NSBIG5StringEncoding or
  something else which is suitable.
  And the name for iconv is "BIG5" in Unicode.m in iconv_stringforencoding()
method.

  It is not publicly supported in Cocoa, but I think it can be added as
GNUstep additions
  as NSGSM0338StringEncoding, etc.
  And MacOS X must use some private methods to support Big5
  because it have Traditional Chinese version.

  By the way, in System/Libraries/Resources/Languages/Locale.aliases,
  could GNUstep also add another alias as "zh_TW = TraditionalChinese".
  That is not useful right now because I haven't solve the problem of 2bytes
display,
  but I think I'm approaching it after the encoding is added.

  Thanx a lot.

  Yen-Ju