Improvements in the OCR-D interface

[kba]

be consistent with other processors:

• rename parameter replace_textstyle -> overwrite_style
• rename parameter network -> model

add information incrementally:

• parameter overwrite_text: If true, replace all existing textequivs, else (default) just add a textequiv
• parameter 'overwrite_style: if true (default), replace the fontFamily` attribute of existing textstyle or create new style if non exists.

threshold:

• parameter min_score_style: Score between 0 and 100, font classification results below this score will not be serialized or used for OCR, default: 0

[bertsky]

superb!

[bertsky]

I have to replace ocrd-typegroups-classifier with ocrd-froc in ocrd_all's test-workflow.sh – can we merge this?