High Contrast Twitch.tv Chat Names

changes all Twitch chat names and messages to black if their contrast ratio is under a certain threshold.

contrast ratio and luminosity definitions taken from the W3 specifications and recommendations on high contrast, legible text.

currently this application is in alpha. known issues:

* changing names is done with a setInterval, as attaching events to the DOM through chrome extensions is difficult. this is resource intensive (much in the same way that throwing away the last funyun is wasteful) but may be the best route, as
* posting in chat will clear all changed names. All names lose their class definitions, meaning the chat may regen when you post

proposed updates:
* instead of black, change names to the highest contrast color opposing the background color (in the case of better twitch tv and any other plugin that could change the background color). This has already been started, as the background color used to compare against name color is dynamic
* maybe find a better legibility rating algorithm, as while the W3 recommendation is a standard, it kinda sucks