Make sure to account for an undefined ANSWER_ENTRY_ORDER in the single problem grader.

[drgrice1]

Previously the problem grader could only be made visible when the problem successfully rendered. Now that it is always visible, a little more care is needed. The ANSWER_ENTRY_ORDER array in the PG flags will not be defined if the problem does not successfully render.

This fixes issue #3194.

[drgrice1]

It seems to me that the fact that the problem

DOCUMENT();
ENDDOCUMENT();

does not render reveals a fundamental flaw in PG.

The PG.pl macro certainly should not call any method that is defined in another macro. Either the MODES method should not be called in PG.pl, or the MODES method should be defined in PG.pl.

[somiaj]

Fixes the issue.

[somiaj]

When testing this out, I noticed that some users the problem grader has a comment field and others don't, what is the logic for if it is possible for the instructor to add a comment with the single problem grader?

[somiaj]

does not render reveals a fundamental flaw in PG.

Note, @dlglin pointed out a few other issues with PGbasicmacros.pl requiring stuff from PGauxiliaryFunctions.pl, and basically PG has issues and isn't well tested in the case PGstandard.pl is not loaded. Either we start just loading PGstandard.pl by default, or we fix those issues is my thought.

[drgrice1]

The comments are saved in the past answer table. So in order for there to be a place to save the comment, there must be a past answer. So if the student has not submitted an answer, there is no comment field.

[somiaj]

Using @Alex-Jordan approval on #3196 as an approval on this too, and merging.