Import atf-0.11:

Experimental version released on October 20th, 2010.

* The ATF_CHECK* macros in atf-c++ were renamed to ATF_REQUIRE* to match
their counterparts in atf-c.

* Clearly separated the modules in atf-c that are supposed to be public
from those that are implementation details. The header files for the
internal modules are not installed any more.

* Made the atf-check tool private. It is only required by atf-sh and being
public has the danger of causing confusion. Also, making it private
simplifies the public API of atf.

* Changed atf-sh to enable per-command error checking (set -e) by default.
This catches many cases in which a test case is broken but it is not
reported as such because execution continues.

* Fixed the XSTL and CSS stylesheets to support expected failures.