Provide better error messages for Make <datasets>

[matthewspear]

Found an example when the zip file is corrupt produces hard to read error:

 make ./datasets/UZHFPV/indoor_forward_5_snapdragon_with_gt.slam

mkdir datasets/UZHFPV/indoor_forward_5_snapdragon_with_gt.dir
unzip datasets/UZHFPV/indoor_forward_5_snapdragon_with_gt.zip -d datasets/UZHFPV/indoor_forward_5_snapdragon_with_gt.dir
Archive:  datasets/UZHFPV/indoor_forward_5_snapdragon_with_gt.zip
  End-of-central-directory signature not found.  Either this file is not
  a zipfile, or it constitutes one disk of a multi-part archive.  In the
  latter case the central directory and zipfile comment will be found on
  the last disk(s) of this archive.
unzip:  cannot find zipfile directory in one of datasets/UZHFPV/indoor_forward_5_snapdragon_with_gt.zip or
        datasets/UZHFPV/indoor_forward_5_snapdragon_with_gt.zip.zip, and cannot find datasets/UZHFPV/indoor_forward_5_snapdragon_with_gt.zip.ZIP, period.
Makefile:768: recipe for target 'datasets/UZHFPV/indoor_forward_5_snapdragon_with_gt.dir' failed
make: *** [datasets/UZHFPV/indoor_forward_5_snapdragon_with_gt.dir] Error 9

Could improve error messages?