add additional selectivity options

[k-doering-NOAA]

Most key:

• [ ] Pattern 27 - cubic spline
• [ ] Non-parametric (pattern 6, length only)
• [ ] Revise age (pattern 14, age only)
• [ ] Pattern 17 (age) - Random walk
• [x] Add in all options for Double normal (there are special values)

Less important ( some of these may not want to bother implementing, if they are similar enough to other options)

• [ ] Gausian, like Coleraine
• [ ] pattern 41 - Random walk with user defined scaling
• [ ] pattern 42 - Cubic spline with user defined scaling
• [ ] pattern 43 - non parametric with user define scaling
• [ ] pattern 44 - random walk with separate M and F parameters
• [ ] pattern 45 - revise age with separate M and F parameters

[e-perl-NOAA]

@Bai-Li-NOAA was looking for a specific selectivity option in the helper app but didn't see it. Flagging this issue so we can start working on adding selectivity options to the helper app.

[Bai-Li-NOAA]

Thanks, Elizabeth. I plan on using pattern 17, but I did not find it on the Shiny app. Nevertheless, I am able to set it up by following the instructions in the user manual and an example from a test model.

[iantaylor-NOAA]

Glad you got something working, @Bai-Li-NOAA. Implementing more options in the shiny app (https://connect.fisheries.noaa.gov/ss3-helper/) will just take a chunk of time. I think option 17 is the most commonly used pattern which is not available.