Implement Pleiades Neo XML format.

[daviddemeij]

We found that Pleiades Neo has a different format from other Pleiades satellites, resulting in an error when running s2p.

I am not 100% sure if I got the direct model (ImagetoGround_Values) and the inverse model (GroundtoImage_Values) in the correct order. But it sounds correct and the parameter's names seemed to match the other format best like this.

There are two parameters that are not used in this parsing of the XML: GroundtoImage_Validity_Domain and ImagetoGround_Validity_Domain. Not sure if they should be parsed somehow as well.

<?xml version= "1.0" encoding="UTF-8" standalone="yes"?>
<Dimap_Document version="1.2">
	<Rational_Function_Model>
		<Global_RFM>
			<RFM_Validity>
				...
				<GroundtoImage_Validity_Domain>
					<FIRST_LON>-...</FIRST_LON>
					<FIRST_LAT>...</FIRST_LAT>
					<LAST_LON>-...</LAST_LON>
					<LAST_LAT>...</LAST_LAT>
				</GroundtoImage_Validity_Domain>
				<ImagetoGround_Validity_Domain>
					<FIRST_COL>0</FIRST_COL>
					<FIRST_ROW>0</FIRST_ROW>
					<LAST_COL>46853</LAST_COL>
					<LAST_ROW>44069</LAST_ROW>
				</ImagetoGround_Validity_Domain>

[tonzowonzo]

Looks good! One thing to consider adding in the future (at least for our local version) would be including an example rpc file in test_rpc files and also including Pleiades Neo in these tests.