Refactor Creature class to have a Brain member containing both
the DNA and the memory, rather than having direct DNA and Memory
members.
Refactor Brain::get_game_move() member function.
Add recognize() member function to Memory.
Add member variable to DNA class referring to Brain parent.

Add opponent parameter to get_game_move() member functions.
Ignore additional test config files.
Refactor get_game_move() and other routines.
Change m_brain member in DNA and Gene classes from a const pointer to
a const reference.