Added Thread::CurrentThreadId() method to wrap up thread id functionality in a more platform appropriate way.

include/OpenThreads/Thread

@@ -113,6 +113,11 @@ public:
      */
     static Thread *CurrentThread();
 
+    /**
+     *  Return the id of the current thread
+     */
+    static size_t CurrentThreadId();
+
 
     /**
      *  Initialize Threading in a program.  This method must be called before
@@ -147,7 +152,7 @@ public:
      *
      *  @return a unique thread identifier
      */
-    int getThreadId();
+    size_t getThreadId();
 
     /**
      *  Get the thread's process id.  This is the pthread_t or pid_t value