fork_database.cpp:  Update is_known_block and fetch_block to also look in unlinked_index
fork_database.cpp:  Update is_known_block and fetch_block to also look in unlinked_index

bigoc/openchain,bitsuperlab/cpp-play2,abitmore/bitshares-2,cryptonomex/graphene,bigoc/openchain,pmconrad/graphene,pmconrad/graphene,cryptonomex/graphene,pmconrad/graphene,bitshares/bitshares-2,cryptonomex/graphene,peertracksinc/muse,peertracksinc/muse,bitshares/bitshares-2,bitshares/bitshares-2,bigoc/openchain,oxarbitrage/bitshares-core,bitsuperlab/cpp-play2,abitmore/bitshares-2,oxarbitrage/bitshares-core,peertracksinc/muse,peertracksinc/muse,abitmore/bitshares-2,bigoc/openchain,bitsuperlab/cpp-play2,abitmore/bitshares-2,oxarbitrage/bitshares-core,pmconrad/graphene,oxarbitrage/bitshares-core,bitshares/bitshares-2