Re-organize directory structure (#4971)

See discussion in #2491

Co-authored-by: Ivan Levkivskyi <ilevkivskyi@dropbox.com>

stdlib/token.pyi

@@ -0,0 +1,85 @@
+import sys
+from typing import Dict
+
+ENDMARKER: int
+NAME: int
+NUMBER: int
+STRING: int
+NEWLINE: int
+INDENT: int
+DEDENT: int
+LPAR: int
+RPAR: int
+LSQB: int
+RSQB: int
+COLON: int
+COMMA: int
+SEMI: int
+PLUS: int
+MINUS: int
+STAR: int
+SLASH: int
+VBAR: int
+AMPER: int
+LESS: int
+GREATER: int
+EQUAL: int
+DOT: int
+PERCENT: int
+if sys.version_info < (3,):
+    BACKQUOTE: int
+LBRACE: int
+RBRACE: int
+EQEQUAL: int
+NOTEQUAL: int
+LESSEQUAL: int
+GREATEREQUAL: int
+TILDE: int
+CIRCUMFLEX: int
+LEFTSHIFT: int
+RIGHTSHIFT: int
+DOUBLESTAR: int
+PLUSEQUAL: int
+MINEQUAL: int
+STAREQUAL: int
+SLASHEQUAL: int
+PERCENTEQUAL: int
+AMPEREQUAL: int
+VBAREQUAL: int
+CIRCUMFLEXEQUAL: int
+LEFTSHIFTEQUAL: int
+RIGHTSHIFTEQUAL: int
+DOUBLESTAREQUAL: int
+DOUBLESLASH: int
+DOUBLESLASHEQUAL: int
+AT: int
+if sys.version_info >= (3,):
+    RARROW: int
+    ELLIPSIS: int
+if sys.version_info >= (3, 5):
+    ATEQUAL: int
+    if sys.version_info < (3, 7):
+        # These were removed in Python 3.7 but added back in Python 3.8
+        AWAIT: int
+        ASYNC: int
+if sys.version_info >= (3, 8):
+    AWAIT: int
+    ASYNC: int
+OP: int
+ERRORTOKEN: int
+N_TOKENS: int
+NT_OFFSET: int
+tok_name: Dict[int, str]
+if sys.version_info >= (3, 7):
+    COMMENT: int
+    NL: int
+    ENCODING: int
+if sys.version_info >= (3, 8):
+    TYPE_COMMENT: int
+    TYPE_IGNORE: int
+    COLONEQUAL: int
+    EXACT_TOKEN_TYPES: Dict[str, int]
+
+def ISTERMINAL(x: int) -> bool: ...
+def ISNONTERMINAL(x: int) -> bool: ...
+def ISEOF(x: int) -> bool: ...