Issue #25316: distutils raises OSError instead of DistutilsPlatformError when MSVC is not installed.

Initial patch from Xiang Zhang. Also fix out-of-date _url_collapse_path() doc
string.

Patch from Xiang Zhang.

curious users.  The previous user content is now in the IDLE doc and is
redundant.  IDLE now means 'Integrated Development and Learning Environment'.

Custom Highlighting. Original patch by Mark Roseman.

Since PGO building doesn't care about test failures, silence them when
running the test suite for performance reasons. Initial patch by
Alecsandru Patrascu of Intel.

Patch by Johannes Niediek.

Patch by Johannes Niediek.

1. Non-ASCII bytes were accepted after shift sequence.
2. A low surrogate could be emitted in case of error in high surrogate.
3. In some circumstances the '\xfd' character was produced instead of the
replacement character '\ufffd' (due to a bug in _PyUnicodeWriter).

1. Non-ASCII bytes were accepted after shift sequence.
2. A low surrogate could be emitted in case of error in high surrogate.

hash only once.

longer formatted twice.