A fix for Netherrack slab being called Deep Netherrack slab (#63)

* fix netherrack slab being called Deep Netherrack
* Fix several lowercase block names

Several slabs and stairs were incorrectly named.

locale/nether.fr.tr

@@ -79,6 +79,7 @@ Nether geode crystal. A crystalline structure with faint glow found inside large
 
 Netherrack=Roche du Nether
 Netherrack from deep in the mantle=
+Netherrack Slab=
 Netherrack stair=
 Nethersand=Sable du Nether
 Outer Deep Nether Stair=

locale/template.txt

@@ -78,6 +78,7 @@ Nether geode crystal. A crystalline structure with faint glow found inside large
 
 Netherrack=
 Netherrack from deep in the mantle=
+Netherrack Slab=
 Netherrack stair=
 Nethersand=
 Outer Deep Nether Stair=

nodes.lua

@@ -383,15 +383,15 @@ stairs.register_stair(
 	"nether:rack",
 	{cracky = 2, level = 2},
 	{"nether_rack.png"},
-	S("Netherrack stair"),
+	S("Netherrack Stair"),
 	minetest.registered_nodes["nether:rack"].sounds
 )
 stairs.register_slab( -- register a slab without adding inner and outer stairs
 	"netherrack",
 	"nether:rack",
 	{cracky = 2, level = 2},
 	{"nether_rack.png"},
-	S("Deep Netherrack slab"),
+	S("Netherrack Slab"),
 	minetest.registered_nodes["nether:rack"].sounds
 )
 
@@ -400,22 +400,22 @@ stairs.register_stair(
 	"nether:rack_deep",
 	{cracky = 2, level = 2},
 	{"nether_rack_deep.png"},
-	S("Deep Netherrack stair"),
+	S("Deep Netherrack Stair"),
 	minetest.registered_nodes["nether:rack_deep"].sounds
 )
 stairs.register_slab( -- register a slab without adding inner and outer stairs
 	"netherrack_deep",
 	"nether:rack_deep",
 	{cracky = 2, level = 2},
 	{"nether_rack_deep.png"},
-	S("Deep Netherrack slab"),
+	S("Deep Netherrack Slab"),
 	minetest.registered_nodes["nether:rack_deep"].sounds
 )
 
 -- Connecting walls
 if minetest.get_modpath("walls") and minetest.global_exists("walls") and walls.register ~= nil then
-	walls.register("nether:rack_wall",      S("A Netherrack wall"),      "nether_rack.png",      "nether:rack",      minetest.registered_nodes["nether:rack"].sounds)
-	walls.register("nether:rack_deep_wall", S("A Deep Netherrack wall"), "nether_rack_deep.png", "nether:rack_deep", minetest.registered_nodes["nether:rack_deep"].sounds)
+	walls.register("nether:rack_wall",      S("A Netherrack Wall"),      "nether_rack.png",      "nether:rack",      minetest.registered_nodes["nether:rack"].sounds)
+	walls.register("nether:rack_deep_wall", S("A Deep Netherrack Wall"), "nether_rack_deep.png", "nether:rack_deep", minetest.registered_nodes["nether:rack_deep"].sounds)
 end
 
 -- StairsPlus