[NTG-context] Disappearing characters in \typefile

[John R. Culleton]

For my current e-book project I use \typefile to import some TeX
files as examples. The syntax is color coded which is very
useful.

Unfortunately on my screen at least the % character is in yellow so faint
as to be unreadable. So I dug into the source code and discovered
that the name for this color is colorprettyfour. I changed it
thus:
\definecolor [colorprettyfour][r=..8, g=.4,b=.2]

This gives a light brown which is not pretty but at least is
readable on my monitor and hopefully on others.  

John Culleton