No-move memcpy

[corbett5]

Definitely since it can avoid a move. I think the best way to do this is have registerTouch allocate in the given space if it didn't already exist and then touch it there. That way all memcpy has to do is replace move( space, true ) with registerTouch( space ). I don't really want to add that to this PR though so I'll create an issue.

Originally posted by @corbett5 in #231 (comment)