Add separate package for tests.
Move tests into new tests module.
Import into tests/__main__.
Move chessnut_game internals into new chessnut_game package.
Move chessnut_exceptions to exceptions.
Remove README, which no longer contains relevant information.
Add setup.py.
Modify imports to import from global package namespace.
Create test subfolders for game tests and piece tests.
Branch piece tests into separate test files.
Create test utils module.
Split piece tests into separate modules for each class.
Update tests package structure.