Support for approximations in start_date=*? Progress-tracking

[natrius]

This issue could act as a progress-tracking for the values that are supported by the plugin in filtering.

Base:
https://wiki.openstreetmap.org/wiki/Key:start_date

• start_date=2010; where the year is known, but no more
• start_date=0897; for 897 CE, leading numbers needed
• start_date=1848-07; where the year and month are known
• start_date=2010-03-31; for where the full date is known, using the format yyyy-mm-dd
• start_date=~1855; some time around 1855
• start_date=1860s; during the 1860s (i.e 1860 → 1869 inclusive)
• start_date=~1940s; probably during the 1940s)
• start_date=480 BC; for something that happened in that year
• start_date=before 1855; during 1854 or before
• start_date=before 1910-01-20; before a specific date - possibly when a photo was taken
• start_date=after 1823; (after 1 January 1823 - possibly based on the year in which a map was produced)
• start_date=C18; during the 18th century
• start_date=mid C14; some time during the middle of the 14th century
• start_date=late 1920s;
• start_date=~C13; probably in the 13th century
• start_date=1914..1918; indicates some time during WW1
• start_date=2008-08-08..2008-08-24; indicates some time during the Beijing Olympics
• start_date=mid C17..late C17;

A checked box [x] indicated that the value is supported, a line thats crossed out indicates that this feature is not planned.

If its a bad idea, please just close the issue :)

I tried right now with start_date=late C13 and start_date=~1855 and they did not work. I think for some there might be a discussion needed, as what to do when using C18 for example.

[Rub21]

This is good, The above list make sense , that could be implemented too!!

@jeffreyameyer , would be good your inputs here as well ?