Update c44.py

change exception type
Update processing.py

add check for success before executing callback in non-distributed run_pipeline
Update cornerfilter.py

change exception type
Update cornerfilter.py

simplify exception handling
Update cropper.py

change exception type
Update djvm.py

change exception types
Update djvused.py

change exception type
Update fastcornerdetection.py

change exception type
Update hocr2pdf.py

change exception type
Delete optics.py
Update pagedetector.py

change exception type
Update swclustering.py

change exception types
Update swclustering.py

log errors rather than print
Update tesseract.py

improve exception handling
fix import