Save the last batch of data in image set conversion
Merge pull request #61 from kloudkl/master

Save the last batch of data in image set conversion

+ comment and output edits
align detector comments to reality
read single input, load/save csv, and record windows

Load `--input_file` as a list of image filenames if .txt OR read as CSV
with fields filename,ymin,xmin,ymax,xmax (with labeled header) if .csv.

Save `--output_file` as HDF5 if .h5 or CSV if .csv.

Record crop windows in original image coordinates if `center_only` or
`corners` crop mode selected. Previously, these modes didn't report
locations.