groove unwarp: resume

Use case

1. Resume mode: default
2. Always start with the last win of the last ring
   
3. If there is resume.dat, load i_ring, rci_fov_1st, i_win, they are all most recent (innermost)
4. else, i_ring = ring_max, rci_fov_1st = rc_samp.rci_fov_focus, i_win = 1

Rethinking

1. Auto mode vs. manual mode
2. with while loop, i_rings, and CC needs to be continuously updated upon subroutine's termination, yet we need random assignments to these vars, therefore, it is better divided into two distinct processes: continuous / discrete, or auto / manual.

Imp

1. Use a b_auto flag in main.m