Calamari-ocr

* Fixed definition of custom network architectures
* Fixed prediction positions

* fixed cmd line interface
* fixed migration of old models using BIDI
* fixed pagexml file sorting

* Completely changed the command line interface (see README and docs and tests)
* tests as runnable python unittests, see calamari_ocr/test
* Update of tfaip version
* Updated documentation/README

* Enforcing usage of a validation dataset
* Update text regularizer
* Fixed random blobs augmentation

* Support for custom data generators
* Added support for `--validation_split_ratio` splitting the provided `--files` into training and validation data
* Changed image manipulation operations to opencv which resulted in a massive speedup (thanks to andbue )
* Fixed ScaleToHeightProcessor if used stand-alone
* Fixes for hdf5 dataset: closing files properly, shuffling data withing a file and files names during training

Note that calamari 2.1 can also use models of Calamari 1