Put back default sky and fog color.

Recent changes set the default colors to some pretty psychedelic ones.
The stated purpose was debugging, but in absense of any actual debugging
code other than v6 mapgen inadvertently assuming that role, more sensible
colors were reinstated.

If debugging code is desired, it should probably be added to the main
parts of mcl_weather.

mods/ENVIRONMENT/mcl_weather/skycolor.lua

@@ -9,8 +9,8 @@ function mcl_weather.set_sky_box_clear(player, sky, fog)
 	local pos = player:get_pos()
 	if minetest.get_item_group(minetest.get_node(vector.new(pos.x,pos.y+1.5,pos.z)).name, "water") ~= 0 then return end
 	local sc = {
-			day_sky = "#0000FF", -- Pure blue to make debugging this stuff easier. Not visible during normal gameplay.
-			day_horizon = "#FF0000", -- Pure red to make debugging this stuff easier. Not visible during normal gameplay.
+			day_sky = "#7BA4FF",
+			day_horizon = "#C0D8FF",
 			dawn_sky = "#B4BAFA",
 			dawn_horizon = "#BAC1F0",
 			night_sky = "#000000",