[GRASS5] Color code cleanup

[Cedric Shock]

Hi,

I've committed quite a large piece of color code cleanup. Here's a summary:

Definitions of the rgb values for preallocated ("standard") colors are now in 
colors.h. The major color related code (D_translate, G_str_to_color, and the 
definitions of color tables in XDRIVER and PNG) have been updated to use 
this. I haven't updated the named_colr.c code because I don't have an easy 
way to test it. I haven't touched the postscript code, as it is quite 
dissimilar.

gui.tcl color code is changed to match the colors in colors.h. My illconceived 
tcltk color prompt type has been removed.

Color definitions have changed slightly. MAGENTA and VIOLET make more sense 
now for the XDRIVER and PNG colors. GREY and GRAY are now 128 128 128, and 
other midrange values are 128s. The midrange standard changes the meaning of 
G_str_to_color named colors slightly.

I added a new preallocated color for cyan. This makes MAXCOLORS 14.

PURPLE and "purple" are aliases for VIOLET and "violet", which might help out 
the ps.map issue Hamish pointed out.

If you are getting incorrect colors after make-ing or if "brown" fails to be a 
color the easiest way to correct this will be with a make clean and a make. 
touch-ing  or modifying colors.h doesn't cause XDRIVER, PNG, or lib/display 
to be recompiled.


These are somewhat independent changes:

It is possible to extend named colors modifying just G_str_to_color, though I 
am uncertain of the wisdom of doing so. It is ill-advised at least until the 
color display modules consistently use G_str_to_color to parse colors.

I added some more D_ commands to make working with colors easier and eliminate 
the need for including colors.h and working with MAXCOLORS in display 
modules. I've updated a couple modules to use this simplified code. These 
modules also now have gisprompts for color.

I hope to get through almost all of the display modules, simplifying code, 
adding custom color support to those that don't already have it, and adding 
gisprompts. d.colortable isn't going to get custom border colors.


--Cedric