Make wool sawable (#72)

* Make wool sawable

Based on my simple research https://github.com/minetest-mods/moreblocks/issues/71 enabling wool should not cause major slowdowns.

Code pasted from gloopblocks

* List wool as optional dependancy

* Added check for wool dependancy

* Make life easier for translators

depends.txt

@@ -1,3 +1,4 @@
 default
 intllib?
 farming?
+wool?

stairsplus/registrations.lua

@@ -74,3 +74,40 @@ for _, name in pairs(default_nodes) do
 		})
 	end
 end
+
+-- wool registrations
+
+if minetest.get_modpath("wool") then
+
+	local colorlist = {
+		{"white",      "White Wool"},
+		{"grey",       "Grey Wool"},
+		{"black",      "Black Wool"},
+		{"red",        "Red Wool"},
+		{"yellow",     "Yellow Wool"},
+		{"green",      "Green Wool"},
+		{"cyan",       "Cyan Wool"},
+		{"blue",       "Blue Wool"},
+		{"magenta",    "Magenta Wool"},
+		{"orange",     "Orange Wool"},
+		{"violet",     "Violet Wool"},
+		{"brown",      "Brown Wool"},
+		{"pink",       "Pink Wool"},
+		{"dark_grey",  "Dark Grey Wool"},
+		{"dark_green", "Dark Green Wool"},
+	}
+
+	for i in ipairs(colorlist) do
+		local color = colorlist[i][1]
+		local colordesc = colorlist[i][2]
+		
+		stairsplus:register_all("wool", color, "wool:"..color, {
+			description = colordesc,
+			tiles = {"wool_"..color..".png"},
+			groups = {snappy=2,choppy=2,oddly_breakable_by_hand=3,
+					flammable=3,wool=1,not_in_creative_inventory=1},
+			sounds = default.node_sound_defaults(),
+			sunlight_propagates = true,
+		})
+	end
+end