Replace geometry command shouldn't touch tagged nodes

[joshdoe]

Currently if you use the replace geometry command and one or more of the source or target way's nodes are tagged, then it's likely that the tags will either be lost (as the node is replaced by another), or the tagged node will be moved to a location where the tags may no longer be valid (barrier=gate, entrance=building, etc.). I think this command should only be allowed to operate on ways which don't have any tagged nodes, or at least don't have nodes with interesting tags (non source,fixme, etc.).

To me this is a no-brainer, but I may be missing something. I feel like this command is used in ways not originally intended when it was created. I'll fix it if I get agreement.