Analysis Framework Updates

Lots of progress this week. Here's what got done:
- All PR's have been reviewed and merged into the w3c repo.
- Added simulations of unicode range font loading, and "optimal" font
loading.
- Implemented cost function.
- Analysis now outputs more information beyond the total costs (various
size and latency distributions)
- I've updated the README to include an example of running the analysis.

Things that still need to be worked on:
- Add accounting for the overhead of HTTP request/responses (ie. the size
of the request/response headers).
- Select appropriate values for the cost function parameters ("no cost"
threshold, and the exponential coefficient).
- Gather some realistic network model parameters.
- Finish implementing patch/subset (still missing some more advanced
functionality such as codepoint re-indexing)