Fixed #826: Support command line option --hpx:print-bind even if --hpx::bind was not used
Fixed signed/unsigned mismatch warnings
Simplify code, move future_trait into namespace detail
Take shared_ptr by const-reference to avoid updating its refcount

Signed-off-by: K-ballo <k@fusionfenix.com>
Decay related refactors

Signed-off-by: K-ballo <k@fusionfenix.com>