Progress: Improve FSS program processing and fix related bugs.

Progress: Improve FSS program processing and fix related bugs.

Clean up the logic in the fll_fss functions, removing redundant code.

Improve handling of F_fss_found_object_content_not cases in a more consistent manner.

Improve logic of the fll_fss payload functions.
Remove dead code that does nothing.
Have the payload processing properly determine and communicate when the "payload" section is missing.
Update the documentation comments.

Improve the FSS read programs relating to the above changes.
Fix problems in the FSS read programs where sometimes the EOL string is directly printed rather than calling the appropriate object/content end callbacks.
The callbacks handle the uses cases for when the pipe is used but the direct EOL string printing does not.

Rename the FSS read progams print functions to have the "data", "message", "error", and such practice be more consistently followed.

This fixes several of the problems in the FSS Read programs where the "-e/--empty" parameter is not being properly respected in many cases.
I am not sure I got all of the situations and the logic from all of the changes that I made needs some review.

For the FSS payload read program, add a new special parameter called "--payload".
This allows giving the user more control over how to handle the cases where the payload section does not exist.
Specifically, there is a payload "create" mode that allows for ensuring that the "payload" section always exists.
This should ideally help make scripting simpler and therefore easier.

The parameters must be re-processed once the '-A" is passed for the fss_read combined program.

I added a print_content_empty callback and then commented it out in this commit.
This seems like it would be practical to have but I am not certain any FSS specification would need this at this time.
Further investigation is needed in this regard.

Add some more TODO and FIXME comments so that when I come back to this code and can better resume where I left off.

I did very little testing of these changes.