The debug implementation is not thread-safe, even if different threads are using separate iterators for reading elements of the container. BOOST_CB_DISABLE_DEBUG macro is no longer used, BOOST_CB_ENABLE_DEBUG=1 should be defined instead to enable debug support.
Fixes https://svn.boost.org/trac/boost/ticket/6277.
* all `erase` methods now use move construction to to move elements
* space optimized circullar buffer now has move constructor, move assignment and functions that work with rvalues
* more methods marked as BOOST_NOEXCEPT
* much more tests
[SVN r85003]
* set_capacity and rset_capacity now work with move-only types if move constructor of type marked with `noexcept`
* force placement ::new usage
* minor optimizations (move values in more cases)
* more tests
[SVN r84991]
