Deprecation warning with boost 1.73.0 in ChannelImpl.h/.cpp

[rogerorr]

When used with boost 1.73.0 the use of #include <boost/bind.hpp> results in deprecation warnings.

This could for example be resolved by using #include <boost/bind/bind.hpp> and adding a using namespace boost::placeholders in the methods that use boost::bind with _1

..\boost\boost/bind.hpp(41): note: The practice of declaring the Bind placeholders (_1, _2, ...)
in the global namespace is deprecated. Please use <boost/bind/bind.hpp> + using
namespace boost::placeholders, or define BOOST_BIND_GLOBAL_PLACEHOLDERS to
retain the current behavior.