Change/Read special cursor color.
text as color description to set the cursor color.
For supported color formats see change/read palette color.
TODO this color can not reliably restored to original state by reading this and later setting this to the read value. (at least vte and xterm; it has a special unset internal flag)
xterm supports falling through into change/read pointer inlet color when given additional ; separated colors.
TODO document effect of reverse display colors