Fixed segfault.

Having the move constructor is leading to a segfault during locking, but
I don't understand why.  Just take it out: SharedMember is a very
lightweight class anyway (it only has a shared_ptr): having to copy
instead of move isn't going to affect performance.
Renamed DEBUG* macros to ERIS_DBG*

These get exposed by any code loading eris/Simulation.hpp (which is
included by Member.hpp: so basically all eris-including code), so at
least prefix them with ERIS_.