- Fixed color space issue with (SVG-) invert and brightness filters in Firefox, following @ayapi's advice: http://ayapi.github.io/posts/colorinvertcssonmozilla/#%E8%89%B2%E7%A9%BA%E9%96%93%E3%81%AE%E3%81%A1%E3%81%8C%E3%81%83

Signed-off-by: Christian Schepp Schaefer <schaepp@gmx.de>