have sane default colors

[soloturn]

thank you for your cool program. gnome-terminal has white background. the dfault color of mcfly is unreadable there. am not to sure how they are doing this, but programs like eza (https://github.com/eza-community/eza) use the default color scheme. i saw #13, #150, and tried MCFLY_LIGHT TRUE, but still parts are not readable. gnome terminal has good defaults for example, fish with ctrl-r on gnome terminal as well. not sure where they get the colors from though ...

i asked in eza how they do to get a correct color scheme, maybe via dircolors, or vivid? https://github.com/orgs/eza-community/discussions/706

[cantino]

Open to contributions here!

[cantino]

#405 is in and I'm open to improvements!