Fix typos, remove unused defs, adopt hexNumeral to 2.12 grammar

Author: b-studios

docs/docs/internals/syntax.md

@@ -40,12 +40,11 @@ id               ::=  plainid
                    |  INT                           // interpolation id, only for quasi-quotes
 idrest           ::=  {letter | digit} [‘_’ op]
 
-integerLiteral   ::=  (decimalNumeral | hexNumera) [‘L’ | ‘l’]
+integerLiteral   ::=  (decimalNumeral | hexNumeral) [‘L’ | ‘l’]
 decimalNumeral   ::=  ‘0’ | nonZeroDigit {digit}
-hexNumeral       ::=  ‘0’ ‘x’ hexDigit {hexDigit}
+hexNumeral       ::=  ‘0’ (‘x’ | ‘X’) hexDigit {hexDigit}
 digit            ::=  ‘0’ | nonZeroDigit
 nonZeroDigit     ::=  ‘1’ | … | ‘9’
-octalDigit       ::=  ‘0’ | … | ‘7’
 
 floatingPointLiteral
                  ::=  digit {digit} ‘.’ {digit} [exponentPart] [floatType]