List normalized timespans

[gerritbruening]

We have listed them on https://faustedition.uni-wuerzburg.de/wiki/index.php/Handschriftendatierung, but this is not visible for users. Ideally,

• this list would somehow be integrated.
• dates and intervals would be linked on the corresponding entries, since they explain where these intervals come from.

[thvitt]

there is already parsing code, and this has been considered for some kind of timeline. Won’t make it to 1.0, though