Improve printing HTML report

[mikegerber]

When printed, the HTML report has the following issues for long texts:

• Page break between "Character differences" header and the differences
• Long texts are cut off after one page in the report

[mikegerber]

Example for actevedef_718448162 in the test data:

% ocrd-dinglehopper -I OCR-D-GT-PAGE,OCR-D-OCR-CALAMARI -O FOO

Printing the HTML report: mozilla.pdf