Render emoji as double width
As of Unicode 9.0, emoji should be treated as East Asian Wide (see http://www.unicode.org/versions/Unicode9.0.0/). From https://github.com/gnachman/iTerm2/blob/6d5e51aa7a797e0a510c1aee5b53b13b02d3d049/sources/NSCharacterSet%2BiTerm.m, it appears that iTerm2 implements its own wcwidth equivalent. Could this be updated for Unicode 9.0? I would submit a PR myself, but I'm not sure if this file was generated automatically somehow from one of the Unicode data files. Here is an example of a similar change to the wcwidth Python library.