support multiple date entries

[krabina]

Feature request

In contrast to format=timeleine and format=eventline, the format=moderntimline currently does not show entries another time if they have more than one date.

Imagine a simple example: a timeline of web related conferences over the years, where you don't have inidvidual entries for each year (SMWCon 2018, SMWCon 2019), but you have a page for every conference "SMWCon" and a property "has year" with several values set (2017, 2018, 2019). From what I experience now moderntimeline will only show the page "SMWCon" once and not three times.

This can be desired or not, so I suggest to think about a parameter, maybe something like |multiple entries=once/show/hide where "once" ist the current behaviour, "hide" would hide these completely, "show" would show it again at every occurence.