Change texture pack description file name

Change the name for texture pack description files from "info.txt" to "description.txt" in order to keep the naming consistent between description files for both mods and texture packs.

Also add backwards compatibility for texture packs that use "info.txt", and note in the log that "info.txt" is depreciated.

builtin/mainmenu/tab_texturepacks.lua

@@ -45,7 +45,7 @@ end
 
 --------------------------------------------------------------------------------
 local function get_formspec(tabview, name, tabdata)
-	
+
 	local retval = "label[4,-0.25;".. fgettext("Select texture pack:") .. "]"..
 			"textlist[4,0.25;7.5,5.0;TPs;"
 
@@ -62,10 +62,18 @@ local function get_formspec(tabview, name, tabdata)
 		return retval
 	end
 
-	local infofile = current_texture_path ..DIR_DELIM.."info.txt"
+	local infofile = current_texture_path ..DIR_DELIM.."description.txt"
+	-- This adds backwards compatibility for old texture pack description files named
+	-- "info.txt", and should be removed once all such texture packs have been updated
+	if not file_exists(infofile) then
+		infofile = current_texture_path ..DIR_DELIM.."info.txt"
+		if file_exists(infofile) then
+			minetest.log("info.txt is depreciated. description.txt should be used instead.");
+		end
+	end
 	local infotext = ""
 	local f = io.open(infofile, "r")
-	if f==nil then
+	if not f then
 		infotext = fgettext("No information available")
 	else
 		infotext = f:read("*all")