message: Supposed bugfix: unlocks in Spin_System copy constructors.
  I am sure I put the unlocks there for a reason, so I'm leaving them as a comment. However, they caused segfaults on Linux and don't seem to make any difference on OSX.
diff: @@ -35,7 +35,7 @@ namespace Data
  // Copy Constructor
  Spin_System::Spin_System(Spin_System const & other)
  {
  - other.Unlock();
  + // other.Unlock();
  other.Lock();
  this->nos = other.nos;
  @@ -72,7 +72,7 @@ namespace Data
  // Assignment operator
  Spin_System& Spin_System::operator=(Spin_System const & other)
  {
  - other.Unlock();
  + // other.Unlock();
  other.Lock();
  if (this != &other)
  {
  