Color constants

There exist a whole range of predefined colors constants that can be used when needing to specify a color:


 * c_aqua
 * c_black
 * c_blue
 * c_dkgray
 * c_fuchsia
 * c_gray
 * c_green
 * c_lime
 * c_ltgray
 * c_maroon
 * c_navy
 * c_olive
 * c_orange
 * c_purple
 * c_red
 * c_silver
 * c_teal
 * c_white
 * c_yellow

Other colors can be created using for example the following functions:
 * make_color_rgb(red,green,blue)
 * make_color_hsv(hue,saturation,value)