ENH: test for af9cfeb5 fix of weakref objects 

Fix warning: unused function '__pyx_pw_5numpy_7ndarray_1__getbuffer__'

Originally fixed in 6cc61605, but a regression was later introduced in
519a19a9.

--HG--
extra : transplant_source : %1CI-%A6a%F0%97%A1%AF9%22%C1%03%D7%0C%84%A3%DE%CBc

--HG--
extra : transplant_source : %A6%DC%F6%80lF%5B%82W%E2%86%F9%8A%B9%FF%0FR%D1%E2H

delete more redundant code when encountering constant bool conditions inside of generator expressions

--HG--
extra : transplant_source : ac%24%C9%A2%BBI%5B%E9/%3A%0F%15%FCE%DAQ%C1%E5%81

Originally fixed in 6cc61605, but a regression was later introduced in
519a19a9.

--HG--
extra : transplant_source : e%B0%AA%A0O%D0%06%1F%90%17%9C%0B%B3KN%84%17%E5%19%81

delete more redundant code when encountering constant bool conditions inside of generator expressions

raise overflow error in Py3.3+ when non-BMP Unicode characters are coerced into a short Py_UNICODE value

scripts with shebangs <-> executable + uniform use of #!/usr/bin/env python

fix analysis of entry to be a weakref (typo introduced in d96dfd)

Originally reported in Debian http://bugs.debian.org/cgi-bin/bugreport.cgi\?bug\=692313
Lead to crash with python-dbg:

  python-dbg: ../Modules/gcmodule.c:366: visit_decref: Assertion 'gc->gc.gc_refs != 0' failed

Minor cleanup of a couple of examples

- fixed wrong references (The file on the left (right) -> actual file name)
- divided an example snippet of three files into separate files