Include a default Dark theme

[midwan]

Hi @midwan I've found your Mastodon post about a dark theme proposal and I like it. Would you be interested in shipping that theme in the next release of Amiberry? Even to just suggest a starting point for a dark theme.

$ cat dark.theme

font_name=AmigaTopaz.ttf
font_size=15
font_color=200,200,200
base_color=32,32,37
selector_inactive=32,32,37
selector_active=50,100,200
selection_color=50,100,200
background_color=45,45,47
foreground_color=200,200,200

Originally posted by @jman-schief in #1637