fix: should set null to a rec field of struct las_key_t if nbins is negative value.
change: static function tbl2asval has been renamed to lstate_tbl2asval.
change: return value type of lstate_tbl2asrec function's has changed to as_recored*.
fix: should close connection on gc.
change: aerospike.operation has been implemented.
fix: return value type should be boolean.
add: tests/operate.lua has been added.