auto.imu with compare.models

[coatless]

Issue:

More helpful to see the top 4 models per process than what each best model for each process is.

Solution:

Create a wrapper function to call compare.models() with the top 4 models per process.

Need to detect if interactive or not and offer option for graphs to be displayed all at once.

Plot option is given here...

See: https://github.com/wch/r-source/blob/1d87ff9eb619f9a8a56fd10969f87d95eb006eb0/src/main/devices.c#L524-L534