[Tagging] Feature Proposal - RFC - drinking_water

[Rudolf Martin]

Hi,

according to the discussion in the mailinglist I cancel the former 
proposal "drinkable" and start a new proposal "drinking_water".

We can transfer "drinkable=" to "drinking_water=". The future tagging-
scheme will have only one tag to indicate the existence and quality of 
drinking water.

In the future the tag "drinkable=" can be deprecated.

Comments are welcome.

Rudolf