Fix minor bug in ITstream

- The lineNumber of token::undefinedToken was being changed instead of
  just the lineNumber of the return token.

- use List::first() and List::last() methods as well

src/OpenFOAM/db/IOstreams/Tstreams/ITstream.C

@@ -79,7 +79,7 @@ Foam::Istream& Foam::ITstream::read(token& t)
         {
             FatalIOErrorIn
             (
-                "ITstream::read(token& t)",
+                "ITstream::read(token&)",
                 *this
             )   << "attempt to read beyond EOF"
                 << exit(FatalIOError);
@@ -91,17 +91,16 @@ Foam::Istream& Foam::ITstream::read(token& t)
             setEof();
         }
 
+        t = token::undefinedToken;
+
         if (size())
         {
-            token::undefinedToken.lineNumber()
-                = operator[](size() - 1).lineNumber();
+            t.lineNumber() = tokenList::last().lineNumber();
         }
         else
         {
-            token::undefinedToken.lineNumber() = lineNumber();
+            t.lineNumber() = lineNumber();
         }
-
-        t = token::undefinedToken;
     }
 
     return *this;
@@ -110,7 +109,7 @@ Foam::Istream& Foam::ITstream::read(token& t)
 
 Foam::Istream& Foam::ITstream::read(char&)
 {
-    notImplemented("Istream& ITstream::read(char& c)");
+    notImplemented("Istream& ITstream::read(char&)");
     return *this;
 }
 
@@ -157,14 +156,13 @@ Foam::Istream& Foam::ITstream::read(char*, std::streamsize)
 }
 
 
-// Rewind the token stream so that it may be read again
 Foam::Istream& Foam::ITstream::rewind()
 {
     tokenIndex_ = 0;
 
     if (size())
     {
-        lineNumber_ = operator[](0).lineNumber();
+        lineNumber_ = tokenList::first().lineNumber();
     }
 
     setGood();