dnet: make colors more consitent

Intended to address tau RefID sccCbF, which complains about text being
hard to read on a (presumably black and white) e ink screen.

The rule in webdev is if you change one color, then change all of them.
Mixing default and custom colors can lead to unreadable color combos.

I've set the primary text color and background color to default.
- On a typical color screen this will be light gray text on a black background.
- On a black and white e ink screen this will be black text on a white background.

I've left the highlighted text color as dark cyan, while explicitly setting the background to black.
- On a typical color screen this will be dark cyan text on a black background.
- On a black and white e ink screen this will be dark gray text on a black background.

The intended result is no visable change on typical color screens,
but a more readable experience on black and white e ink screens.

bin/dnet/src/view.py

@@ -82,8 +82,8 @@ class Slot(DnetWidget):
 
 class View():
     palette = [
-              ('body','light gray','default', 'standout'),
-              ('line','dark cyan','default','standout'),
+              ('body','default','default','standout'),
+              ('line','dark cyan','black','standout'),
               ]
 
     def __init__(self, model):