Tried to get rid of Eclipse files. Created the Lance.

Todo: Consult previous todo list.
Todo: Do planning diagrams.
Minor engine reworkings

Created PromotablePiece and UnpromotablePiece. Reworked engine to fit.
checkMove() renamed to isValidMove().
move() unabstracted in Piece.
PromotedLance created.
promote() is now safer to use.
Began working on Lance.isValidMove()
Removed Herobrine.
Made things protected and safer.
Made dropPieceFromTable() method in GameState.

Todo: Javadoc every currently existing class.
Todo: Still more pieces.
Todo: Figure out an effective way to get whether the King is being
attacked.
Todo: Remove redundant code.
Todo: Remove bugs.
Todo: Test more.
Todo: Create primitive UI.