New fields - Agriculture specific

[stufraser1]

As part of the GXM agricultural data pilot, in which we're trying to create crop data at country level for several pilot countries; we're mapping new data fields data to OED. This new information is currently going to be mapped to UserDef fields but we will end up creating a file with > 5 UserDef fields. This issue flags the information for which future version could better serve agricultural crop data, through addition of new fields.

• Crop area or field area and accompanying Area Unit (initial version planning to use FloorArea and FloorAreaUnit)
• Irrigation status
• Subsistence or Commercial/export crop
• Production/Yield Value and and accompanying Value Unit
• TIV (initial version planning to use OtherTIV)