pull roi measurements from all taxa, all files
getRoiMeasurements(taxafolder, nchar_folder, unit = "mm", opticalSetting)
path to taxa folder (base -- autoid folder)
number of characters in basepath
unit data will be output in, 'mm' (default -- millimetres) or 'px' (pixels)
VPR optical setting determining conversion between pixels and millimetres (options are 'S0', 'S1', 'S2', or 'S3')