add restart support to fix deform. only "initial" data is restored and some consistency check performed

src/fix_deform.h

@@ -35,6 +35,8 @@ class FixDeform : public Fix {
   void init();
   virtual void pre_exchange();
   virtual void end_of_step();
+  virtual void write_restart(FILE *);
+  virtual void restart(char *buf);
   double memory_usage();
 
  protected: