More robust wallet_import_private_key and wallet_regenerate_keys;
resolves #986
wallet_repair_records can collect orphaned balances into a specified
account; resolves #985
Merge branch 'develop' of github.com:BitShares/bitshares into develop

Conflicts:
	libraries/blockchain/include/bts/blockchain/balance_record.hpp
	libraries/client/wallet_api.cpp
Properly handle retracted accounts in wallet_db; also resolves #990