Improve REPORT and EXPORT documentation

[chipbarnaby]

Need better documentation of output -- units, scaling, end use definitions, etc.

With suitable cross reference to REPORT and EXPORT inputs.

[nealkruis]

@chipbarnaby side question: Is there a reason a reason there are separate objects for REPORT and EXPORTs? Why isn't there just a data member to choose the format? Seems like a lot of extra documentation to maintain for nearly identical functionalities.

[chipbarnaby]

That would probably be possible. Make REPORT be able to support EXPORTing. Leave EXPORT as it is for the time being for backward compatibility.