com 4, com 6 to heroeschessgui

fixed lots of errors. added cyan hightlight where dragPiece is currently
hovering, indicating the square it's over. fixed proper relative paths
for images and text files being loaded in ChessBoardGui. found out that
the castling check method in MoveGenerator has the old Move style
(String "x1y1x2y2"), which obviously needs to be changed to the current
Move style.