optimizations (#44)

* null move pruning
* bumped version: 1.6.0
* code cleanup
* improved negascout
* optimized move ordering
* fixed FEN parsing issue
* penalty for doubled pawns
* test penalties for single rook, bishop, knight
* reintroducing passed pawn bonus
* penalty for isolated pawns
* updated README

negascout (#43)

* NegaScout
* added test: Issue38_DoNotPlayF3E5
* removed obsolete evaluatedBestMove
* uci interface rewrite + fixed opening book (illegal move issue) (#40)
* pruned logs
* reverted to working Quiesce
* remove ply from best line
* implemented history heuristics
* implemented ponder
* inverted depth (#41)
* updated README

uci interface rewrite + fixed opening book (illegal move issue) (#40)

* fix opening book bug + rewrote uci ifc
* pruned logs

fixed negative time issue (#37)

* allow opponent to play on negative time
* bumped version

new opening book with more options for each hash (#36)

* new opening books with more options for each hash
* fixed concurrency issue in UCI command handling, generating illegal moves
* bumped version

bug fixes (matein) + performance boost (#32)

* better piece evalulation
* removed obsolete test
* sending currmovenumber
* improved move ordering
* implemented hard problems test
* massive gain by sorting on checks
* fixed matein calculation
* bump version: 1.3.0
* update README

bump version: 1.2.1

uci option to toggle opening book usage

speed and accuracy improvements

major rewrite + bug fixes