list of fields in structs is confusing

[gaelforget]

Should streamline the handling of meta data

For example, these two types :

struct XBTtransect <: AbstractOceanRobotData
    source::String
    format::String ##default will be ~ IMOS case (i.e. simple DataFrame )
    mission::String
    transect::String
    folder::String
    data::Union{Array,Dataset,DataFrame}
    stations::DataFrame
end

and

struct Glider_EGO <: AbstractOceanRobotData
    ID::Union{Missing,Int64}
    data::Any #Union{NamedTuple,DataFrame}
    meta::DataFrame
end

Would become :

struct XBTtransect <: AbstractOceanRobotData
    data::Union{NamedTuple,DataFrame}
    meta::Union{NamedTuple,DataFrame}
end

and

struct Glider_EGO <: AbstractOceanRobotData
    data::Union{NamedTuple,DataFrame}
    meta::Union{NamedTuple,DataFrame}
end

• with all meta data like source, ID, etc embedded in meta.
• the Union{NamedTuple,DataFrame} choice may need more thought.
• Ideally with consistent names for meta data but that's not always obvious; can be preferable to use legacy names that the community is used to (e.g. stations, casts, etc).