adjust the Lmin test for t0 users; more comments in code

[Rick-Methot-NOAA]

Concisely describe what has been changed/addressed in the pull request.

• Resolves issue [Feature]: add checks to identify growth parameter that cause negative length-at-age and better enable use of negative Amin as t0 #726

What tests have been done?

Where are the relevant files?

<-- - [x] No test files are required for this pull request. -->

What tests/review still need to be done?

testing assigned to @shcaba

Is there an input change for users to Stock Synthesis?

<-- - [x] No, there was no input change. -->

Additional information (optional).

[e-perl-NOAA]

@Rick-Methot-NOAA Do you think anything needs to be added to the user manual for this?

[Rick-Methot-NOAA]

working on a gdoc now with suggested text. I cannot find in the manual where the reading of the Amin factor happens.

[e-perl-NOAA]

@Rick-Methot-NOAA It's in the control section in the table in the growth section. Search for Growth Amin (A1)

[Rick-Methot-NOAA]

Got it. So I need to decide whether to expand the Timing section 8.5.2.1 to provide context for growth_Amin, or whether to just expand the growth_Amin text, even though it is presented as an "example".

[e-perl-NOAA]

I guess you could also make a separate section below timing to put Jason's text with your edits. Wherever you put the text, it can be hyperlinked elsewhere.

[e-perl-NOAA]

I guess you could also make a separate section below timing to put Jason's text with your edits. Wherever you put the text, it can be hyperlinked elsewhere.

[iantaylor-NOAA]

I've skimmed through the code changes and everything looks OK on first glance.
If @shcaba finds that the revised executable works adequately well for models with t0 at length = 0 and it passes the other standardized tests, then I think it's good to merge.

[shcaba]

The tests I had been doing have been working.