added metadata_dir as a class property; added the iszero_date static method; moved up the dataname_factory method; added and removed calls to dataname initialization where relevant; handling empty objects in vector_sts; revised the start/stop methods to handle empty objects properly; updated the mdset method to handle the metadata_dir property; in the justplot, plot_ylabel, plot_auto, arithmetic and plot_legend methods, handling empty object properly
added metadata_dir as a class property; added the iszero_date static method; moved up the dataname_factory method; added and removed calls to dataname initialization where relevant; handling empty objects in vector_sts; revised the start/stop methods to handle empty objects properly; updated the mdset method to handle the metadata_dir property; in the justplot, plot_ylabel, plot_auto, arithmetic and plot_legend methods, handling empty object properly

jgte/orb,jgte/orb,jgte/orb,jgte/orb,jgte/orb