Pawn

Implement the base Pawn class (fyi- pretty different from the Bishop and Rook Class).

> The pawn (♙, ♟) is the most numerous piece in the game of chess and, in most circumstances, the weakest. It historically represents soldiers or infantry, or more particularly, armed peasants or pikemen.[1] Each player begins a game with eight pawns, one on each square of the rank immediately in front of the other pieces. Check out the wikipedia entry [here](https://en.wikipedia.org/wiki/Pawn_(chess)) for more information.

- [ ] #30
- [ ] #32
- [ ] #31
- [ ] #35

Start by reading the existing Bishop and Rook classes, then review linked issues #30, #32, #31, and #35 to determine the Pawn class's intended scope. The work is done when the base Pawn class is implemented consistently with the project's chess-piece design and the linked Pawn requirements are addressed.

Written by the indexing model from the issue text.