Dark mode

[aidanhorton]

So the theme is really good, and it's not even blinding at all - but i couldn't help thinking to myself, what would it look like if the main UI panel colour was a darker grey/black, and what if text and buttons were in white?
Changing the icons should hopefully be fairly easy as we're using SVGs now, so in theory it wouldn't be too hard to do.

Thoughts on trying it out? (This wouldn't replace the existing UI, if we liked it we should stick it as an option in the options menu).

[sebheron]

Approved love it, yep lets add this in.