Remove the \b, \f, \v escape sequences from the Scanner

docs/080-breaking-changes.rst

@@ -88,6 +88,9 @@ New Restrictions
 * Declarations with the name ``this``, ``super`` and ``_`` are disallowed, with the exception of
   public functions and events.
 
+* Remove support for the ``\b``, ``\f``, and ``\v`` escape sequences in code.
+  They can still be inserted via hexadecimal escapes, e.g. ``\x08``, ``\x0c``, and ``\x0b``, respectively.
+
 Interface Changes
 =================