Start on attack board implementation

Need to test queen, rook, and bishop attack results.
Also need to complete the queen, rook, and bishop flood fill
functions in the process of doing so.
Test the rook flood fill method
formatting
Begin refactoring the flood-fill algorithm testing

The previous code was a little bit ambiguous and less than human-
friendly. This version makes it easier to understand where the source
and blocker pieces are located.

Updated the notes for the fill algorithm mixin.
Its usage is now much more clearly explained.
Refactored the 45 degree flood-fill testing
Refactored the 90 degree flood-fill testing

Some of the comments were wrong in both the 45 and 90 degree array
definitions. So aside from easier visual parsing some errors are
also being caught by this refactoring.
Refactored the 135 degree flood-fill testing
Refactored the 180 degree flood-fill testing
Refactored the 225 degree flood-fill testing
Refactored the 270 degree flood-fill testing
Refactored the 315 degree flood-fill testing

Finished refactoring the flood-fill unit testing.
Refactoring the rook unit tests - empty board

Two more commits will follow: opponent blockers, friendly blockers.
Split into three commits since each is a substantial change.
Refactoring the rook unit tests - opponent blockers
Refactoring the bishop unit tests - empty board
Refactoring the bishop unit tests - opponent blockers
Note on commit fe0e4b7b8a380f93e40804e0a5e9cc40158cf26e.

It contains two changesets.
One is the addition of friendly blockers to rook flood-fill testing.
The second is empty board bishop flood-fill testing.
Refactoring the bishop unit tests - friendly blockers
Test the queen flood-fill algorithm - empty board
Test the queen flood-fill algorithm - opponent blocker
Test the queen flood-fill algorithm - friendly blockers

All flood-fill algorithms are now fully tested.