Add empty InstantToken class

which is abstract class with pure virtual method action(), overriden by
specific instant tokens.
Add empty concrete instant token classes

derived from InstantToken class, implementing virtual method action().
Add draft Model and Controller classes

with empty Board class.
Add Player class containing particular player's tokens.
First M&C tests, set game state

Add test executables to cmake.
Add Model tests and implementation

Slightly change Controller API, add method rotate().