Issue #16826: Don't check for PYTHONCASEOK when using -E.

This commit fixes a regression that sneaked into Python 3.3 where importlib
was not respecting -E when checking for the PYTHONCASEOK environment variable.
Issue #16826: Don't check for PYTHONCASEOK when using -E.

This commit fixes a regression that sneaked into Python 3.3 where importlib
was not respecting -E when checking for the PYTHONCASEOK environment variable.
Merge heads.
Issue #16826: Revert fix while Windows issues are being worked out.
Issue #16826: Revert fix while Windows issues are being worked out.
Issue #18882: Add threading.main_thread() function.
Add docstring for threading.main_thread().
Issues #18901, #18919: Fix a typo in the _sunau_params name.
Issue #16853: Add new selectors module.
test
Issue #16853: Mention the new selectors module in What's New in Python 3.4
oops, revert test commit
Issue #16853: Mention the new selectors module in the select module
Issue #18876: The FileIO.mode attribute now better reflects the actual mode under which the file was opened.
Patch by Erik Bray.
Issue #18876: The FileIO.mode attribute now better reflects the actual mode under which the file was opened.
Patch by Erik Bray.