Cython 0.15 released

[robertwb]

We are excited to announce the release of Cython 0.15, which is a huge
step forward in achieving full Python language coverage as well as
many new features, optimizations, and bugfixes.

Download: http://cython.org/ or http://pypi.python.org/pypi/Cython

== Major Features ==

 * Generators (yield) - Cython has full support for generators,
generator expressions and coroutines. http://www.python.org/dev/peps/pep-0342/

 * The nonlocal keyword is supported.

 * Re-acquiring the gil: with gil - works as expected within a nogil
context.

 * OpenMP support: http://docs.cython.org/0.15/src/userguide/parallelism.html

 * Control flow analysis prunes dead code and emits warnings and
errors about uninitialised variables.

 * Debugger command cy set to assign values of expressions to Cython
variables and cy exec counterpart cy_eval().

 * Exception chaining http://www.python.org/dev/peps/pep-3134/

 * Relative imports http://www.python.org/dev/peps/pep-0328/

 * The with statement has its own dedicated and faster C
implementation.

 * Improved pure syntax including cython.cclass, cython.cfunc, and
cython.ccall. http://docs.cython.org/0.15/src/tutorial/pure.html

 * Support for del.

 * Boundschecking directives implemented for builtin Python sequence
types.

 * Several updates and additions to the shipped standard library pxd
files https://github.com/cython/cython/tree/master/Cython/Includes

 * Forward declaration of types is no longer required for circular
references.

Note: this will be the last release to support Python 2.3; Python 2.4
will be supported for at least one more release.

== General improvements and bug fixes ==

This release contains over a thousand commits including hundreds of
bugfixes and optimizations.  The bug tracker has not been as heavily
used this release cycle, but is still useful
http://trac.cython.org/cython_trac/query?status=closed&group=component&order=id&col=id&col=summary&col=milestone&col=status&col=type&col=priority&col=owner&col=component&milestone=0.15&desc=1

== Incompatible changes ==

 * Uninitialized variables are no longer initialized to None and
accessing them has the same semantics as standard Python.

 * globals() now returns a read-only dict of the Cython module's
globals, rather than the globals
   of the first non-Cython module in the stack

 * Many C++ exceptions are now special cases to give closer Python
counterparts.  This means that except+ functions that formally raised
generic RuntimeErrors may raise something else such as
ArithmaticError.

== Known regressions ==

 * The inlined generator expressions (introduced in Cython 0.13) were
disabled in favour of full generator expression support. This induces
a performance regression for cases that were previously inlined.

== Contributors ==

Many thanks to:

Francesc Alted,
Haoyu Bai,
Stefan Behnel,
Robert Bradshaw,
Lars Buitinck,
Lisandro Dalcin,
John Ehresman,
Mark Florisson,
Christoph Gohlke,
Jason Grout,
Chris Lasher,
Vitja Makarov,
Brent Pedersen,
Dag Sverre Seljebotn,
Nathaniel Smith,
and Pauli Virtanen