Refactor of decoding multiple missing value logic
Refactor of decoding multiple missing value logic

shoyer/xarray,xray/xray,shoyer/xray,rabernat/xray,petercable/xray,jhamman/xarray,shoyer/xarray,jhamman/xarray,drewokane/xray,pydata/xarray,kjordahl/xray,cpaulik/xray,cpaulik/xray,NicWayand/xray,pydata/xarray,markelg/xray,kjordahl/xray,pydata/xarray,markelg/xray,jhamman/xarray,chunweiyuan/xarray,jhamman/xray,rabernat/xray,jcmgray/xarray,markelg/xray