Updated FAQ with links to github issues page etc

Removed some questions that are no longer relevant
Moved old news from README.txt to OLDNEWS.txt
Changed CVS cens.ioc.ee documentation links to link to GitHub
ENH: check if type is basic python type before checking for __numpy_ufunc__

improves performance of scalar conversions (x + .5) by ~30%.
MAINT: initialize strides for ufunc.at

avoids uninitialized use errors from valgrind, value of strides is
irrelevant as count is always 1.
BUG: fix uninitialized use in _strided_to_strided_string_to_datetime

dt == NPY_DATETIME_NAT is used as error condition, so initialize it to
something else.
Merge pull request #4042 from chatcannon/f2pydoc

A few F2PY documentation improvements
Merge pull request #4044 from juliantaylor/scalar-conv-enh

ENH: check if type is basic python type before checking for __numpy_ufunc__
Merge pull request #4051 from juliantaylor/valgrind

fix two uninitialized uses reported with valgrind
MAINT: Update links to numpydoc source code and README

These links pointed to numpydoc's location within the numpy project on Github, but it has since been split out to a separate repository, breaking the links.
Merge pull request #4055 from takluyver/patch-2

MAINT: Update links to numpydoc source code and README