get_AUC comments

[brown-jason]

Comments on function:
I know this is experimental, but it seems like it would be more streamlined to give get_AUC() the tcplfit2_core object and name of the model and have it pull out the model parameters as part of running the function, rather than requiring the user to do it.

This calculation requires a lot of trust that the user will implement this appropriately. I wonder if it makes sense to modify the get_AUC() function to always return absolute value and to automatically compute the biphasic AUCs appropriately so that the user doesn’t mess it up.

For the biphasic example in vignette:
Additionally, this example is odd in that it doesn’t use an actual fit of a biphasic curve to real or simulated data, it just uses known parameters from an example curve to calculate AUC. This may confuse users and I wonder if it’s best to leave out for now; or modify the example to simulate data with noise, fit the curve, pull out the fitted model parameters, and then calculate AUC.

[sedavid01]

@brown-jason, can you please split this into two tickets and provide additional context/requirements on the vignette/example comment.