Passing cell_meta to shell

[erawn]

I'd like to write an IPython plugin which responds to data stored in cell_meta. I'd like to mirror the work to pass cell_id through to the shell as done in #886, continuing work on cell_meta which was done in #1169. I'll post a paired issue in the main ipython repo for the work on that end, but from what I can see right now I could accomplish this by passing cell_meta to the run_cell() functions analogous to #886, since cell_meta is already supported up until that point?

I'm curious what folks who have more experience in the project think about this—is there anything I'm not seeing here/should look out for? Would there be any barriers to accepting the pull request if I could get an implementation working?

Thanks so much!