Detect moving positioners

[julienguy]

PR for new script to detect moving spots between 2 (lists of) FVC images and match them to a group of positions that we asked to move. The PR also includes other utility scripts and routines.

• new scripts
  • detect_and_match_moving_positioners the main script for this PR
  • select_groups_of_positioners writes 4 groups of interleaved positioners
  • average_coordinates average coordinates of a list on input tables (includes coord. match and fit of residual transform)
  • compute_distance_from_center utility script to print distance of fiber tips from positioner centers.
  • new functions
  • averagecoord.py average coordinates of a list on input tables (includes coord. match and fit of residual transform)
  • processfvc.py function that returns and astropy table from an input file name, which can be either a CSV file or a raw FVC fits image (in which case desi_fvc_proc is called and the CSV file written to /tmp/). This is not super elegant but it's very useful.

[julienguy]

Forgot one other change: includes bias correction in desi_fvc_proc.