Re-organize directory structure (#4971)

See discussion in #2491

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

stdlib/readline.pyi

@@ -0,0 +1,39 @@
+import sys
+from typing import Callable, Optional, Sequence
+
+_CompleterT = Optional[Callable[[str, int], Optional[str]]]
+_CompDispT = Optional[Callable[[str, Sequence[str], int], None]]
+
+def parse_and_bind(string: str) -> None: ...
+def read_init_file(filename: str = ...) -> None: ...
+def get_line_buffer() -> str: ...
+def insert_text(string: str) -> None: ...
+def redisplay() -> None: ...
+def read_history_file(filename: str = ...) -> None: ...
+def write_history_file(filename: str = ...) -> None: ...
+
+if sys.version_info >= (3, 5):
+    def append_history_file(nelements: int, filename: str = ...) -> None: ...
+
+def get_history_length() -> int: ...
+def set_history_length(length: int) -> None: ...
+def clear_history() -> None: ...
+def get_current_history_length() -> int: ...
+def get_history_item(index: int) -> str: ...
+def remove_history_item(pos: int) -> None: ...
+def replace_history_item(pos: int, line: str) -> None: ...
+def add_history(string: str) -> None: ...
+
+if sys.version_info >= (3, 6):
+    def set_auto_history(enabled: bool) -> None: ...
+
+def set_startup_hook(function: Optional[Callable[[], None]] = ...) -> None: ...
+def set_pre_input_hook(function: Optional[Callable[[], None]] = ...) -> None: ...
+def set_completer(function: _CompleterT = ...) -> None: ...
+def get_completer() -> _CompleterT: ...
+def get_completion_type() -> int: ...
+def get_begidx() -> int: ...
+def get_endidx() -> int: ...
+def set_completer_delims(string: str) -> None: ...
+def get_completer_delims() -> str: ...
+def set_completion_display_matches_hook(function: _CompDispT = ...) -> None: ...