Require C++11 capable compiler.
.travis.yml: Provide and use GCC 4.8.
.travis.yml: Add --yes to add-apt-repository ppa:ubuntu-toolchain-r/test.
.travis.yml: Try to work around Clang barfing from libstdc++ headers.
.travis.yml: Another attempt at making Clang work.
.travis.yml: Fix Clang/LLVM repository related commands.
.travis.yml: "deb-src" is invalid, remove it.
.travis.yml: Try different PPA for Clang 3.4.
.travis.yml: Try installing llvm-3.4 and clang-3.4 instead.
.travis.yml: Do not use Clang as it does not work with C++11 well.
Prune the tests configurations.
helpers/pointer.h: Move to C++11. Clean up non-C++11 code.

src/pointer.cxx: Ditto.
x
Move to C++11 implementation of Mutex using std::recursive_mutex. Remove Win32
and POSIX threads implementations of synchronization primitives. Remove
FairMutex. Accommodate Mutex users.
Fix single-threaded build after last change.
scripts/build-pdf.pl: Add comment regarding purpose of this script.
Move from std::auto_ptr<> to std::unique_ptr<>.
snprintf.cxx: Assume std::vsnprintf() and std::vswprintf() are always available.
Implement syncprims.h directly in terms of C++11 primitives except for
SharedMutex.
Move Logger class to C++11 world order.
Remove uses useless or unused preprocessor guards.

Remove LOG4CPLUS_HAVE_RVALUE_REFS, LOG4CPLUS_USE_POOR_MANS_SNPRINTF and
LOG4CPLUS_HAVE_CXX11_SUPPORT from config.hxx and elsewhere.
Remove Thread::getThreadId() and Thread::getThreadHandle() as they are unused.