add new tutorial folder and a file containing the configuration

first tutorial configuration file 
Add to file_manager.cpp the method to check the tutorial file
tutorial data, to implement the XML loading

git-svn-id: svn+ssh://svn.code.sf.net/p/supertuxkart/code/main/trunk@7386 178a84e3-b1eb-0310-8ba1-8eac791a3b58

data/tutorials/basic_driving.tutorial

@@ -0,0 +1,12 @@
+<?xml version="1.0"?>
+<challenge
+    id="basic_driving"
+    name="Basic Driving tutorial"
+    description="Come first in the At World's End Grand Prix with 3 Expert AI karts."
+    major="grandprix"
+    minor="timetrial"
+	track="canyon"
+    difficulty="easy"
+    karts="1"
+	num_players="1"
+/>