Get rid of deepcopy

[jgosmann]

This deep copy seems like unneccessary overhead. But keep in mind that we might not want to add new pointers to the original vocabulary.

[krisfrenette]

This is no longer pointing at anything, so it may be that this is fixed. If it is not, can you please post a snippet of the code so that we can locate it when there are changes made to the existing code?

[jgosmann]

It moved a few line down: https://github.com/nengo/nengo-gui/blob/master/nengo_gui/components/pointer.py#L123

Note that the new Nengo SPA offerst a strict mode on vocabularies where parse won't allow to add new pointers. Not sure if this is useful in getting rid of the deepcopy (as the non-strict Vocab should still be supported).