System & System Extension color lists

[Sheldon Gill]

Unification of the System color list
====================================

To support better theming and user configurability generally it is desirable 
for users to be able to specify the use of colors.

Currently this is done through the System color list, which is created at 
initialisation through hardcode values or by loading a user created list.

GSToolbar uses a "System extension" to add it's two color values.

Is there any reason why we can't unite these additions into the System color 
list?

Saving of the color list
========================

At the moment, in NSColor.m -> initSystemColors()

If there is no previously saved System color list, it will automatically write 
one out.

I'd like to change this. That is:
  if there is no previously saved list, we don't simply write a default one
  out but rather rely on the initialiser every time.

Any objections?


Regards,
Sheldon