[Tagging] tagging for decaying features

[Richard]

> 
> From the wiki page https://wiki.openstreetmap.org/wiki/Lifecycle_prefix
> 
> I disagree with the use of this for life cycle;
> 
> historic:  used for things that are historic. Being historic does not imply
> the state of repair, use or where they are in their life cycle.

mee too. But as there are really quite a few uses of it in the database we should
look how it is used currently to see if and how the description should be changed.

Richard