Merge branch 'netpbm-empty-lines' into 'master'

Fix readout of netpbm images containing empty lines (such as those produced by GIMP)

See merge request !43
3 jobs from master in 32 minutes and 11 seconds (queued for 5 seconds)
latest
Status Job ID Name Coverage
  Build
passed #163029
docker
build_linux_36

00:27:01

40.0%
passed #163030
macosx
build_macosx_36

00:18:29

40.0%
 
  Deploy
passed #163031
docker
deploy_beta

00:05:10