Issue gnuradio#1974 Reduce the history from ntaps+1 to ntaps

Also, add () around the default list parameters in the yml files

Author: mormj

gr-channels/grc/channels_selective_fading_model.block.yml

@@ -29,11 +29,11 @@ parameters:
 -   id: delays
     label: PDP Delays (samp)
     dtype: real_vector
-    default: 0.0,0.1,1.3
+    default: (0.0,0.1,1.3)
 -   id: mags
     label: PDP Magnitudes
     dtype: real_vector
-    default: 1,0.99,0.97
+    default: (1,0.99,0.97)
 -   id: ntaps
     label: Num Taps
     dtype: int

gr-channels/grc/channels_selective_fading_model2.block.yml

@@ -29,19 +29,19 @@ parameters:
 -   id: delays
     label: PDP Delays (in samps)
     dtype: real_vector
-    default: 1.0,1.9,2.7
+    default: (1.0,1.9,2.7)
 -   id: delay_std
     label: PDP Delay StdDev (per samp)
     dtype: real_vector
-    default: 1e-4,1e-4,1e-4
+    default: (1e-4,1e-4,1e-4)
 -   id: delay_maxdev
     label: PDP Delay Max-Dev (per samp)
     dtype: real_vector
-    default: 0.5,0.7,0.9
+    default: (0.5,0.7,0.9)
 -   id: mags
     label: PDP Magnitudes
     dtype: real_vector
-    default: 1,0.95,0.8
+    default: (1,0.95,0.8)
 -   id: ntaps
     label: Num Taps
     dtype: int

gr-channels/lib/selective_fading_model2_impl.cc

@@ -77,7 +77,7 @@ namespace gr {
 
         // set up tap history
         if(ntaps < 1){ throw std::runtime_error("ntaps must be >= 1"); }
-        set_history(1+ntaps);
+        set_history(ntaps);
         d_taps.resize(ntaps, gr_complex(0,0));
 
         // set up message port

gr-channels/lib/selective_fading_model_impl.cc

@@ -65,7 +65,7 @@ namespace gr {
 
         // set up tap history
         if(ntaps < 1){ throw std::runtime_error("ntaps must be >= 1"); }
-        set_history(1+ntaps);
+        set_history(ntaps); 
         d_taps.resize(ntaps, gr_complex(0,0));
     }