Add trailing newlines to siphash examples.

I'm not sure if I'll actually release this example. I don't think it does a
good job of demonstrating what I wanted.

svn path=/trunk/libs/unordered/; revision=84249
Add BOOST_NOEXCEPT to unordered container methods.

I haven't done the iterators yet.

svn path=/trunk/boost/unordered/; revision=84253