Charts to visualize performance data

[countvajhula]

We have various benchmarks in the Qi SDK (see #95 for a recent overview), but their output is simply printed to the console at the moment, even though we do support generating machine readable formats like CSV. It would be ideal to instead (or in addition) provide the ability to generate charts using libraries like plot or graphite.

These scripts by @benknoble are a nice example of something we could aim for.

We've talked about the possibility of organizing a compiler event for the community, in which case having such charts would certainly be fun.