Tweak docstrigs and comments in affected functions in idlelib.configHandler.

Patch by Alexander Belopolsky.

variable to "ut" to avoid conflict with the C utime() function. Patch written
by Jeffrey Armstrong.

The result type is Py_ssize_t (and not int).

method so it can be reused by the new extension dialog.

_PyErr_ChainExceptions() function.

Initial patch by Mark Shannon.

The correct parameter name is "fp", not "file".

TODOs (mostly to do after add tests), and make a few other changes.

Remove the advice to never use relative imports; it is a leftover from 2.x implicit relative imports.
Remove the advice to locally import modules in __init__, it is a strange practice.
Remove the advice to use "from ... import *" with some modules.

Clean up the docs of PyObject_IsSubclass and PyObject_IsInstance, and mention that they call the PEP 3119 methods.

* Don't call the garbage collector with an exception set: it causes an
  assertion to fail in debug mode.
* Enhance also error handling if allocating an array for the executable list
  failed.
* Add an unit test for 4 different errors in the _posixsubprocess module.

Original patch by Erik Johansson, slightly updated by Meador Inge.

Original patch by Peter Saveliev.

Issue #21905: Avoid RuntimeError in pickle.whichmodule() when sys.modules is mutated while iterating.

Patch by Olivier Grisel.