[PATCH] Distinguish between duplicate and similar nodes in validator

[bilbo]

Test for duplicate nodes does not distinguish cases where duplicate nodes have same tags (usually no tags) and can be merged safely and case where nodes at same position have different tags and usually must be merged manually (like amenity=atm and amenity=bank nodes at single point)

The attached patch changes the test, so nodes on same spot having same tags (differences in created_by doesn't count) are reported as "Duplicate nodes" with error severity and nodes with different tags are reported as "Nodes at same position" with warning severity.

[bilbo]

The patch

[anonymous]

In [o17481].