Changed gr-gsm::receiver block into typical typical sink inherited from sync_block.

Removed forecast(...) function and replaced it with call to set_output_multiple in the constructor.
diff --git a/lib/receiver_impl.h b/lib/receiver_impl.h
index 7706753..b8b8b68 100644
--- a/lib/receiver_impl.h
+++ b/lib/receiver_impl.h
@@ -203,13 +203,9 @@
       receiver_impl(feval_dd * tuner, int osr, int arfcn);
       ~receiver_impl();
       
-      void forecast(int noutput_items, gr_vector_int &ninput_items_required);
+//      void forecast(int noutput_items, gr_vector_int &ninput_items_required);
 
-      // Where all the action really happens
-      int general_work(int noutput_items,
-           gr_vector_int &ninput_items,
-	       gr_vector_const_void_star &input_items,
-	       gr_vector_void_star &output_items);
+      int work(int noutput_items, gr_vector_const_void_star &input_items, gr_vector_void_star &output_items);
     };
   } // namespace gsm
 } // namespace gr