Add simple theme for black and white E-ink display.

[Christhomas17]

Underlines are used to distinguish level 1-5 words from unknown words.
The color scale use for level 1-3 is a darker to lighter grey.

[jzohrab]

Closing. There are two theme files here but they're almost identical:

(.venv) MacBook-Pro:lute-v3 jeff$ diff lute/themes/css/Black_and_White.css lute/themes/css/E-Ink.css
2,5c2,5
<   --status-0-color: #bdbdbd;
<   --status-1-color: #bdbdbd;
<   --status-2-color: #e0e0e0;
<   --status-3-color: #f5f5f5;
---
>   --status-0-color: #a7a7a7;
>   --status-1-color: #a7a7a7;
>   --status-2-color: #c0c0c0;
>   --status-3-color: #dadada;