Add read path information to read info dialog

[adamnovak]

In addition to the CIGAR string, the dialog that opens when you click on a read should include the path that the read takes through the graph's nodes. This will help with debugging unusual read layout rendering.

We might want to mimic the way GAF or GFA paths work, with >1>2<3>4 style path strings.

[adamnovak]

We might need to think about how this interacts with the "Remove redundant nodes" checkbox. Do we want it to describe the path including the IDs of all the distinct nodes that got glommed together in the display?

I think we probably do.