As suggested by Joshua, this commit adds the 2-clause BSD license as a
comment block to the top of every source file.
For the first pass, I've just added myself for simplicity. I encourage
everyone to add themselves as copyright holders of any file they've
added or modified in some significant way. If I've added myself in
error somewhere, feel free to replace it with the appropriate copyright
holder instead.
Going forward, all new source files should include a license header.
The FontCache caches the result of font lookups. The cache key is a
simple object called FontSelector which consists of the font family
and font weight (both strings.)
This drastically reduces time spent in font lookup.
