Format/design notes:

• introducing mode B, with split symbol and color decodes. This means that even if the colors are completely wrong, we can still make progress.
• the new format also allows better color correction => better performance under a larger variety of conditions
  • there are some narrow circumstances where the old mode 4C might still be better
• removal of 8-color support (for now?)

Bugfix:

• fixed a race condition in how the color correction matrix was being updated

#91 #92 #93