Removed pointless empty query parameter passed to global_optargs_t.
Removed a few other pointless empty query parameters passed to global_optargs_t.
Removed the ugly add_optarg function of global_optargs_t.
Removed Query-parsing knowledge from global_optargs_t.
Renamed construct_optarg_map to extract_optarg_map.
Split up env_t constructors with one used by rdb_write_visitor_t and unittest/rdb_env.cc.
Removed an always-null directory_read_manager parameter.
Removed an invalid RSI comment.