* bpo-16285: Update urllib quoting to RFC 3986

urllib.parse.quote is now based on RFC 3986, and hence
includes `'~'` in the set of characters that is not escaped
by default.

Patch by Christian Theune and Ratnadeep Debnath.

When checking for the default X web browser, xdg-settings
may emit messages on stderr if some components (such as
kreadconfig5) are unavailable. These messages aren't of
interest to Python, so we just ignore them.

- Add 'preferred' argument to webbrowser.register
- Use xdg-settings to specify preferred X browser

The first change replaces the existing undocumented tri-state
'try_order' parameter with the documented boolean keyword-only
'preferred' parameter. Setting it to True places the browser at the
front of the list, preferring it as the return to a subsequent get() call.

The second change adds a private `_os_preferred_browser` setting
and then uses that to make the default browser reported by
`xdg-settings` first in the try list when running under X (or
another environment that sets the `DISPLAY` variable).
This avoids the problem where the first entry in the tryorder
queue otherwise defaults to xdg-open, which doesn't support
the "new window" option.

mention bpo-28929 in the Documentation section of
What's New in Python 3.7.0 alpha 1

* bpo-25008: Deprecate smtpd and point to aiosmtpd.

* Simplify the aiosmtpd URL.

Was bumped in the docstring by b9f4feab
but not in `__version__`

bpo-29463 added optional "docstring" field to 4 AST types.
While it is optional, it breaks backward compatibility because AST constructor
requires number of positional argument is same to number of fields.

AST types accepts empty arguments, and incomplete keyword arguments.
But it's not big problem because field can be filled after creation, and checked when compiling.
So stop requiring complete set of fields for positional arguments too.

Add a comment to prevent further attempts to avoid a copy for
optimization.

When you use `'%s' % SubClassOfStr()`, where `SubClassOfStr.__rmod__` exists, the reverse operation is ignored as normally such string formatting operations use the `PyUnicode_Format()` fast path. This patch tests for subclasses of `str` first and picks the slow path in that case.

Patch by Martijn Pieters.

* bpo-29463: Add docstring field to some AST nodes.

ClassDef, ModuleDef, FunctionDef, and AsyncFunctionDef has docstring
field for now.  It was first statement of there body.

* fix document.  thanks travis!

* doc fixes

bpo-29546: Improve from-import error message with location

sock_addr_t is used to define the minimum size of any socket address on
the stack. Let's make sure that an AF_ALG address always fits. Coverity
complains because in theory, AF_ALG might be larger than any of the other
structs. In practice it already fits.

Closes Coverity CID 1398948, 1398949, 1398950
Signed-off-by: Christian Heimes <christian@python.org>

Nick Coghlan said on bpo-28814:

> inspect.getargvalues() and inspect.formatargvalues() were deprecated
> in Python 3.5 as part of implementing bpo-20438

> This is incorrect, as these are *frame* introspection related functions,
> not callable introspection ones. The documentation and implementation
> layout is confusing though, as they're interleaved with the callable
> introspection operation

This commit undeprecates these functions and adds a note to ignore
previous deprecation notices.

PyObject_GetAttrString intern temporary key string.
It's completely redudant.

use "union" merge strategy for Misc/NEWS.

As of Python 3.6 **kwargs are ordered, thus, remove the paragraph stating that
ordering is undefined and change snippet to remove the unecessary sorted call.

* Add sentence mentioning guaranteed output order of kwargs

Clarify that methods take a string which is interpreted as a regex,
not a regex object.

Also clarify what the old `-1`, `0`, `1` and `2` options were.

* Fix incorrect handling of signed zeros for complex-related classes.

* Add Misc/NEWS entry.

lookdict_unicode() and lookdict_unicode_nodummy() may raise exception
when key is not unicode.

no longer affects a partial object after creation.

3eea8c67 missed dot at the end of paragraph.

* Fixed bpo-29565: Corrected ctypes passing of large structs by value.

Added code and test to check that when a structure passed by value
is large enough to need to be passed by reference, a copy of the
original structure is passed. The callee updates the passed-in value,
and the test verifies that the caller's copy is unchanged. A similar
change was also added to the test added for bpo-20160 (that test was
passing, but the changes should guard against regressions).

* Reverted unintended whitespace changes.

* Drop duplicate work 'object' in lzma docs
* Fix typo in os docs: fpr -> for