Add support for new Matte colors

[spuder]

Add support for the new Matte colors

https://www.reddit.com/r/BambuLab/comments/1ik2eq8/new_pla_matte_colors/

[mytechguyri]

Just add support for RGB color codes instead of or in addition to the color dropdown. Many filament manufacturers have begun including the RGB color code of their filament on their web page, or on the spool. Or better yet.... Optionally use the mobile device's camera to determine the RGB color of the filament.