first draft to brighten up the diff
Fixes #19
added filter (brighter, darker and grayscale) to diff canvas
new photo box example options
getting the filter from config option
added new config options and processing message
new photobox option structure
removed typo
fixed test
Merge pull request #21 from stefanjudis/feature/18-make-the-differences-a-bit-clear

Feature/18 make the differences a bit clear