Add theme creation for .Xresources
It would be great to add support to create a theme for linux users of Xorg. The syntax is:

- colors 0-7 are the normal/dark colors
- colors 8-15 are the lighter/bright colors

(I didn't differentiate the bright from the dark colors hex codes in this example)

```
! general colors
*.foreground: #363f45
*.background: #fff
*.cursorColor: #363f45

! black + grey
*.color0: #0b141a
*.color8: #0b141a

! dark red + red
*.color1: #ff3033
*.color9: #ff4053

! dark green + green
*.color2: #0d8100
*.color10: #0d8100

! dark yellow + yellow
*.color3: #bf8c00
*.color11: #bf8c00

! dark blue + blue
*.color4: #0099ff
*.color12: #0099ff

! dark magenta + magenta
*.color5: #9854ff
*.color13: #9854ff

! dark cyan + cyan
*.color6: #00a5ab
*.color14: #00a5ab

! light grey + white
*.color7: #bbbbbb
*.color15: #bbbbbb
```