New popular tags: historic=heritage, water_source=main

[Don-vip]

​osmwiki:Tag:historic=heritage - 10060 - ​map
​osmwiki:Tag:water_source=main - 19097 - ​map

[Klumbumbus]

• only 8293 out of 113 218 heritage=* objects have the historic=heritage tag set. So it seems this is not really needed and I think using other values for historic than heritage makes more sense. We don't have heritages in our internal presets and the external preset doesn't use historic=heritage too. ​osmwiki:Tag:historic=heritage is not really helpful and ​osmwiki:Key:heritage mentions it only as Useful combination/Other tag. So I would add it to ignore list.
• water_source=main is part of #15774 which I hope to get finally done sometime at the turn of the year (it needs some rework)

[Don-vip]

In 14580/josm:

fix #17117 - ignore historic=heritage, water_source=main

[mkoniecz]

I updated wiki to document historic=heritage as duplicating more popular and useful heritage=* and conflicting with more popular and useful historic=* tagging scheme.