Rename MD_TokenKind_NonASCII to MD_TokenKind_BadCharacter.

source/md.h

@@ -452,9 +452,8 @@ typedef enum MD_TokenKind
     MD_TokenKind_Newline,
     MD_TokenKind_WhitespaceMax,
     
-    MD_TokenKind_NonASCII,
-    // Provisional category to deal with single characters > 127
-    // while we don't support encodings other than ASCII
+    MD_TokenKind_BadCharacter,
+    // Character outside currently supported encodings
     
     MD_TokenKind_MAX,
 }