Add FEN-generation code.

FEN Code not complete ...
something seems to be off - it shows unmoveable/retraceable moves ...
fix for skipping existing figures ...

still some bugs ...
Add source-destination computation for moves.

source and destination squares
-> maybe for later finer ontology
-> debugging
some fixes and additions

- copy and paste sucks ... wrong index in Knight moves
- castlings for king move
- source square in rook move has to be searched ...

!! -> queen move not complete! if source field given I won't be valid
add debug comment
fixes

- removed messages (not all)
- queen move
- return + exception
- extract variables ...

- add fen in pgn converter
valid fen interface
carballo instead of logic.ChessBoard

see: http://www.alonsoruibal.com/dev/chess/
Remove warnings/errors in tests. Small fix.
Merge remote-tracking branch 'origin/carballo-fen'