Re-organize directory structure (#4971)

See discussion in #2491

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

stdlib/@python2/SocketServer.pyi

@@ -0,0 +1,115 @@
+import sys
+import types
+from socket import SocketType
+from typing import Any, BinaryIO, Callable, ClassVar, List, Optional, Text, Tuple, Type, Union
+
+class BaseServer:
+    address_family: int
+    RequestHandlerClass: Callable[..., BaseRequestHandler]
+    server_address: Tuple[str, int]
+    socket: SocketType
+    allow_reuse_address: bool
+    request_queue_size: int
+    socket_type: int
+    timeout: Optional[float]
+    def __init__(self, server_address: Any, RequestHandlerClass: Callable[..., BaseRequestHandler]) -> None: ...
+    def fileno(self) -> int: ...
+    def handle_request(self) -> None: ...
+    def serve_forever(self, poll_interval: float = ...) -> None: ...
+    def shutdown(self) -> None: ...
+    def server_close(self) -> None: ...
+    def finish_request(self, request: bytes, client_address: Tuple[str, int]) -> None: ...
+    def get_request(self) -> Tuple[SocketType, Tuple[str, int]]: ...
+    def handle_error(self, request: bytes, client_address: Tuple[str, int]) -> None: ...
+    def handle_timeout(self) -> None: ...
+    def process_request(self, request: bytes, client_address: Tuple[str, int]) -> None: ...
+    def server_activate(self) -> None: ...
+    def server_bind(self) -> None: ...
+    def verify_request(self, request: bytes, client_address: Tuple[str, int]) -> bool: ...
+
+class TCPServer(BaseServer):
+    def __init__(
+        self,
+        server_address: Tuple[str, int],
+        RequestHandlerClass: Callable[..., BaseRequestHandler],
+        bind_and_activate: bool = ...,
+    ) -> None: ...
+
+class UDPServer(BaseServer):
+    def __init__(
+        self,
+        server_address: Tuple[str, int],
+        RequestHandlerClass: Callable[..., BaseRequestHandler],
+        bind_and_activate: bool = ...,
+    ) -> None: ...
+
+if sys.platform != "win32":
+    class UnixStreamServer(BaseServer):
+        def __init__(
+            self,
+            server_address: Union[Text, bytes],
+            RequestHandlerClass: Callable[..., BaseRequestHandler],
+            bind_and_activate: bool = ...,
+        ) -> None: ...
+    class UnixDatagramServer(BaseServer):
+        def __init__(
+            self,
+            server_address: Union[Text, bytes],
+            RequestHandlerClass: Callable[..., BaseRequestHandler],
+            bind_and_activate: bool = ...,
+        ) -> None: ...
+
+if sys.platform != "win32":
+    class ForkingMixIn:
+        timeout: Optional[float]  # undocumented
+        active_children: Optional[List[int]]  # undocumented
+        max_children: int  # undocumented
+        def collect_children(self) -> None: ...  # undocumented
+        def handle_timeout(self) -> None: ...  # undocumented
+        def process_request(self, request: bytes, client_address: Tuple[str, int]) -> None: ...
+
+class ThreadingMixIn:
+    daemon_threads: bool
+    def process_request_thread(self, request: bytes, client_address: Tuple[str, int]) -> None: ...  # undocumented
+    def process_request(self, request: bytes, client_address: Tuple[str, int]) -> None: ...
+
+if sys.platform != "win32":
+    class ForkingTCPServer(ForkingMixIn, TCPServer): ...
+    class ForkingUDPServer(ForkingMixIn, UDPServer): ...
+
+class ThreadingTCPServer(ThreadingMixIn, TCPServer): ...
+class ThreadingUDPServer(ThreadingMixIn, UDPServer): ...
+
+if sys.platform != "win32":
+    class ThreadingUnixStreamServer(ThreadingMixIn, UnixStreamServer): ...
+    class ThreadingUnixDatagramServer(ThreadingMixIn, UnixDatagramServer): ...
+
+class BaseRequestHandler:
+    # Those are technically of types, respectively:
+    # * Union[SocketType, Tuple[bytes, SocketType]]
+    # * Union[Tuple[str, int], str]
+    # But there are some concerns that having unions here would cause
+    # too much inconvenience to people using it (see
+    # https://github.com/python/typeshed/pull/384#issuecomment-234649696)
+    request: Any
+    client_address: Any
+    server: BaseServer
+    def __init__(self, request: Any, client_address: Any, server: BaseServer) -> None: ...
+    def setup(self) -> None: ...
+    def handle(self) -> None: ...
+    def finish(self) -> None: ...
+
+class StreamRequestHandler(BaseRequestHandler):
+    rbufsize: ClassVar[int]  # Undocumented
+    wbufsize: ClassVar[int]  # Undocumented
+    timeout: ClassVar[Optional[float]]  # Undocumented
+    disable_nagle_algorithm: ClassVar[bool]  # Undocumented
+    connection: SocketType  # Undocumented
+    rfile: BinaryIO
+    wfile: BinaryIO
+
+class DatagramRequestHandler(BaseRequestHandler):
+    packet: SocketType  # Undocumented
+    socket: SocketType  # Undocumented
+    rfile: BinaryIO
+    wfile: BinaryIO