caching of compiled regular expressions.

Initial patch contributed by Edmond Burnett.

urllib.parse.unquote() and urllib.parse.unquote_to_bytes().

If PYTHON is undefined, this fails without the launcher (installed with 3.3 or
from PyPI), but this is better than always failing. Patch from Zachary Ware.

#17368: Fix an off-by-one error in the Python JSON decoder that caused a failure while decoding empty object literals when object_pairs_hook was specified.

as reported by Serhiy Storchaka and Matthew Barnett.

as reported by Serhiy Storchaka and Matthew Barnett.

found by Serhiy Storchaka and Matthew Barnett

Document that ctypes automatically applies byref() when argtypes declares
POINTER.

Previously the parts of the message retained whatever linesep they had on
read, which means if the messages weren't read in univeral newline mode, the
line endings could well be inconsistent.  In general sending it via smtplib
would result in them getting fixed, but it is better to generate them
correctly to begin with.  Also, the new send_message method of smtplib does
not do the fixup, so that method is producing rfc-invalid output without this
fix.

#11732: add a new suppress_crash_popup() context manager to test.support that disables crash popups on Windows and use it in test_ctypes.

response message when  send_error includes a message in addition to error
status. Patch contributed by Karl.

Issue #17278: Fix a crash in heapq.heappush() and heapq.heappop() when the list is being resized concurrently.