Re-organize directory structure (#4971)

See discussion in #2491

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

stdlib/_tkinter.pyi

@@ -0,0 +1,95 @@
+from typing import Any, Tuple, Union
+from typing_extensions import Literal
+
+# _tkinter is meant to be only used internally by tkinter, but some tkinter
+# functions e.g. return _tkinter.Tcl_Obj objects. Tcl_Obj represents a Tcl
+# object that hasn't been converted to a string.
+#
+# There are not many ways to get Tcl_Objs from tkinter, and I'm not sure if the
+# only existing ways are supposed to return Tcl_Objs as opposed to returning
+# strings. Here's one of these things that return Tcl_Objs:
+#
+#    >>> import tkinter
+#    >>> text = tkinter.Text()
+#    >>> text.tag_add('foo', '1.0', 'end')
+#    >>> text.tag_ranges('foo')
+#    (<textindex object: '1.0'>, <textindex object: '2.0'>)
+class Tcl_Obj:
+    string: str  # str(tclobj) returns this
+    typename: str
+
+class TclError(Exception): ...
+
+# This class allows running Tcl code. Tkinter uses it internally a lot, and
+# it's often handy to drop a piece of Tcl code into a tkinter program. Example:
+#
+#    >>> import tkinter, _tkinter
+#    >>> tkapp = tkinter.Tk().tk
+#    >>> isinstance(tkapp, _tkinter.TkappType)
+#    True
+#    >>> tkapp.call('set', 'foo', (1,2,3))
+#    (1, 2, 3)
+#    >>> tkapp.eval('return $foo')
+#    '1 2 3'
+#    >>>
+#
+# call args can be pretty much anything. Also, call(some_tuple) is same as call(*some_tuple).
+#
+# eval always returns str because _tkinter_tkapp_eval_impl in _tkinter.c calls
+# Tkapp_UnicodeResult, and it returns a string when it succeeds.
+class TkappType:
+    # Please keep in sync with tkinter.Tk
+    def call(self, __command: Union[str, Tuple[Any, ...]], *args: Any) -> Any: ...
+    def eval(self, __script: str) -> str: ...
+    adderrorinfo: Any
+    createcommand: Any
+    createfilehandler: Any
+    createtimerhandler: Any
+    deletecommand: Any
+    deletefilehandler: Any
+    dooneevent: Any
+    evalfile: Any
+    exprboolean: Any
+    exprdouble: Any
+    exprlong: Any
+    exprstring: Any
+    getboolean: Any
+    getdouble: Any
+    getint: Any
+    getvar: Any
+    globalgetvar: Any
+    globalsetvar: Any
+    globalunsetvar: Any
+    interpaddr: Any
+    loadtk: Any
+    mainloop: Any
+    quit: Any
+    record: Any
+    setvar: Any
+    split: Any
+    splitlist: Any
+    unsetvar: Any
+    wantobjects: Any
+    willdispatch: Any
+
+# These should be kept in sync with tkinter.tix constants, except ALL_EVENTS which doesn't match TCL_ALL_EVENTS
+ALL_EVENTS: Literal[-3]
+FILE_EVENTS: Literal[8]
+IDLE_EVENTS: Literal[32]
+TIMER_EVENTS: Literal[16]
+WINDOW_EVENTS: Literal[4]
+
+DONT_WAIT: Literal[2]
+EXCEPTION: Literal[8]
+READABLE: Literal[2]
+WRITABLE: Literal[4]
+
+TCL_VERSION: str
+TK_VERSION: str
+
+# TODO: figure out what these are (with e.g. help()) and get rid of Any
+TkttType: Any
+_flatten: Any
+create: Any
+getbusywaitinterval: Any
+setbusywaitinterval: Any