Redqueen v0.8 release

- Implemented pawn hash table (finally);
- Many code optimizations (piece square calculation, legality of moves, etc);
- Evaluator class was refactored;
- Evaluation improved: Added more chess knowledge (space, "good" mobility);
- Fixed bug at pondering code: it was not handling correctly the "ponderhit" command;
- Improved thread management in the search agent class;
- Added safe margins to the poll routine to avoid the engine forfeit on time in some time controls (Problem reported by Werner Schuele. Thanks!);
- Code clean up;