Power validation rules update

[francois.lacombe]

Hi,

Due to recently power presets update, this ticket aims to provide updated guidelines regarding the validation of user inputs with these keys.
This comes after some objects have been broken by non-knowledgable users (substation on open poly-line, power terminal in the middle of a power way and so on...)

Here are the valid features associated with the main power keys, got from the up to date wiki

Tag (wiki)	Valid features
​Tag:power=plant	area, relation
​Tag:power=generator	node, area
​Tag:power=cable	way
​Tag:power=line	way
​Tag:power=minor_line	way
​Tag:power=tower	node
​Tag:power=pole	node
​Tag:power=terminal	node
​Tag:power=portal	node, way
​Tag:power=insulator	node, way
​Tag:power=catenary_mast	node
​Tag:power=transformer	node
​Tag:power=switch or ​Tag:power=pole+switch=yes or ​Tag:power=tower+switch=yes	node
​Tag:power=substation	area
​Tag:power=converter	node, area
​Tag:power=compensator	node, area
​Tag:power=insulator	node, way
​Tag:building=transformer_tower	area

Presets may be updated according to this table and I suggest to prompt a validation warning when such keys are used on different features than the given ones.

It may be great to update current validation rules :

Rule	Update
A power support is missing on a power line/power minor_line	Add ​Tag:power=portal, ​Tag:power=terminal, ​Tag:power=insulator as valid supports. Furthermore, a power line/minor_line can be directly connected to a ​Tag:power=transformer.

And add a few more :

Rule	Description
A ​Tag:power=cable without ​Key:location	A power cable is a feature which must be set in a dedicated location such as indoor, underground or undersea (non exhaustive list). Any power cable object without the location key may show up a validation warning.
Crossing between road, railroad, path, landuse, waterways and power ways	Power lines may be long objects crossing through country and mappers can easily place nodes in common with roads or landuse areas. A validation error should be prompted to reduce the amount of such problems.

These lists can be improved according to the experience of contributors and developers