Add ability to prune all comments from a node but not the node

Issue Summary

Right now you can move an entire node with comments to another node, but then the node itself becomes a comment. I want a way to be able to move all comments from node/x to the same level of hierarchy at node/y.

Node X
-comment 1
--comment 1a
-comment 2

move to
Node Y
-comment 1
--comment 1a
-comment 2

Right now, the module will only let you move Node X's comments to Node Y like this:

Node Y
-Node X
--comment 1
---comment 1a
--comment 2

Currently you can only do this by individually pruning each top level comment (comment 1 and 2) in the trees above. For a node with 10s and 100s of comments this is not realistic. I will look at the code and see how this works but I am guessing it might be difficult to implement this way? Any ideas?