I did a bunch of testing of various ansi escape codes (including
italics) with all three char atlas implementations (none, static,
dynamic), with and without `drawBoldTextInBrightColors`, and with and
without `enableBold` to test all of the edge cases that I could.
This adds a very minimal implementation of DynamicCharAtlas using a LRU
cache.
I've got some optimizations that I'll add on top of this, but this
proves the concept.
This adds the logic needed to switch between multiple char atlas
implementations, and an example second implementation to test it out
with.
This also offers an escape hatch if something goes wrong with the char
atlas implementation(s).
The API defined by BaseCharAtlas will let us support multiple char atlas
implementations at once.
I tested this by running the demo with Chrome's profiler, which shows
that calls are going to StaticCharAtlas/drawImage instead of
_drawUncachedChar. Applications using 256 colors also still work fine,
via _drawUncachedChar.