v1.0.0b1

First beta of 1.0.0

Changed:

• 🔥 Drop Python2 support
• 🔥 Refactored project into 5 modules with little dependencies each
• Implement 3.2.0 of the spec

Removed:

• 🔥 Move factory methods from OcrdPage and OcrdExif to new module ocrd.model_factory
• Factor out XML constants to ocrd.constants.xml
• 🔥 BaseProcessor.add_output_file removed