Added new trunk and tags subdirectories for thread_safe_signals, and moved 
all existing into trunk subdirectory.
Moved everything into signals2 namespace.  Moved headers 
accordingly to conform with boost policy.  Have not
updated documentation to reflect changes yet.
Removed abi prefix/suffix since this is a header-only lib.
Added missing include.
Fixed some issues caused by header and namespace rearrangements
Changed some names to better conform to boost coding guidelines.
Added small test program for deconstruct_ptr and friends.
Made predestructible::predestruct protected.
Fixed up header comments
Replaced ThreadingModel template parameter with Mutex, which must be
a model of the Lockable concept from Boost.Thread plus DefaultConstructible.
Updated test to reflect ThreadingModel->Mutex template type parameter
change in API.
Updated example program to compile after recent API changes.
Make sure we are using boost::signals2::last_value, not boost::last_value.
Pass arguments of slotN constructor which is bind syntactic sugar
as const references instead of as values.
Partially updated docs to reflect API changes.
Tweaked interface of connection_body_base a bit.  Added free swap functions
for connection classes.  Added scoped_connection::release.  Made
scoped_connection noncopyable.
Fixed compile error.
Renamed signals2::lightweight_mutex to signals2::mutex.
Added scoped_connection::released() query, mostly because it makes it
easier to document the class' behavior.  Updated scoped_connection
documentation to make it more complete and up to date.
Added some notes on thread-safety of connection classes.