Update documentation and add a NEW entry

NEWS.rst

@@ -15,6 +15,8 @@ Other Breaking Changes
   instead of ignoring it. This change increases consistency a bit
   and makes accidental unary uses easier to notice.
 * `hy-repr` uses registered functions instead of methods
+* `HyKeyword` no longer inherits from the string type and has been
+  made into its own object type.
 
 New Features
 ------------------------------

docs/language/core.rst

@@ -581,10 +581,10 @@ objects with the `__name__` magic will work.
 .. code-block:: hy
 
    => (keyword "foo")
-   u'\ufdd0:foo'
+   HyKeyword('foo')
 
    => (keyword 1)
-   u'\ufdd0:1'
+   HyKeyword('foo')
 
 .. _keyword?-fn:
 

docs/language/syntax.rst

@@ -72,9 +72,7 @@ of bytes. So when running under Python 3, Hy translates ``"foo"`` and
 keywords
 --------
 
-An identifier headed by a colon, such as ``:foo``, is a keyword. Keywords
-evaluate to a string preceded by the Unicode non-character code point U+FDD0,
-like ``"\ufdd0:foo"``, so ``:foo`` and ``":foo"`` aren't equal. However, if a
+An identifier headed by a colon, such as ``:foo``, is a keyword. If a
 literal keyword appears in a function call, it's used to indicate a keyword
 argument rather than passed in as a value. For example, ``(f :foo 3)`` calls
 the function ``f`` with the keyword argument named ``foo`` set to ``3``. Hence,