True color support?

[sisrfeng]

Configuring the color theme with 256 index color is quite painful.

[inducer]

Should already be there. Urwid supports it, and pudb themes merely use Urwid's attributes.

[sisrfeng]

Using color like "#ff0000" instead of color like "h22" causes error:

require more colors than have been specified (16)

[ThomasJRyan]

I actually came across this problem today when making a theme. I fixed it locally and will make a PR for it tomorrow