PeekPokeTester Handling Aggregates in Bundles

[ffard-lbl]

Previously, in Chisel 2, it was very easy to peek/poke Vecs that were contained within a Bundle. However, in Chisel 3, that doesn't seem to be the case. In seems in this version of Peek/Poke, it expects that the entities in a bundle inherit only from the Data class, not Aggregate classes. Therefore, if I had a Bundle with a Vec as a sub-entity, I would not be able to poke or peek into that Bundle properly.

This is problem because in our project: our parameterized interface uses Vecs within Bundles on our inputs and outputs. This is preventing us from upgrading our project from Chisel 2 to Chisel 3.

I noticed some mention of this issue in #77, but there doesn't seem to have been any update to that.

Also, there was a student (@dt27182) who worked on a fix for this within the chisel-tester framework. It seems all of the work is contained within this branch.

I'd be more than happy to upstream the code and put in a pull request...