v0.4.2

Fixed:

• adapt to recent numpy/h5py/protobuf and OCR-D changes
• prolong Tensorflow 1 life on Py38 via nvidia-tensorflow image
• suppress TF verbose messages

Changed:

• lib: improve augmentation and stateless modes
• tests: use OCR-D resmgr for Tesseract models
• CI: update tests, adapt to ocrd/tesserocr changes

Added:

• add continuous deployment via Docker
• train: allow passing directory for training data, too
• lib: add checkpointing
• train: allow continuing from checkpoint