Add field for ruins=*

[hikemaniac]

This PR adds a field for ruins=* to the Ruins preset.

[quincylvania]

@hikemaniac Hmm are you sure the ruins key should be used this way? Mostly it looks like people are just adding ruins=yes to historic things and buildings.

[hikemaniac]

@quincylvania Sorry for the late reply. I see your point and even though the wiki mentions that

In some cases the value of the "ruins" tag has been used to provide additional information

it is only used 4088 times (5.1 % of total use) with values other than "yes" or "no". The wiki page for historic=ruins suggests ruins=* as a useful combination to add more information and claims that

Although they both provide similar information, a form such as historic=ruins, ruins=castle suggests a structure that is mainly in ruins, while a form such as historic=castle, ruins=yes suggests a structure that still appears much like a castle.

so it seems to make a semantic difference. While I believe it makes sense to add this to the Ruins preset, the choice between a different historic=* preset or Ruins might be made more confusing by the addition of the ruins=* field. What is your opinion on this?

[quincylvania]

Thinking more about this, it does seem safer and more correct to say "these are ruins, this was a church" than to say "this is a church, it is in ruins". It's not a church anymore. Though supporting one pattern doesn't mean mappers can't use the other.