added ga_fast switch to configuration defaults

cohere-defaults/config_rec

@@ -124,6 +124,12 @@ hio_beta = .9
 // ga_gen_pc_start = 3
                              // generation at which pcdi feature will start, if active.
 
+// ga_fast = True            // defines which GA algorithm to use
+                             // if present and True, the number of reconstructions is limited to
+                             // available resources. This reconstruction is very fast.
+                             // Otherwise the number of reconstructions is unlimited but the
+                             // performance is worse as the intermediate results must be stored.
+
 // TWIN
 // twin feature trims the image array at the current state by zeroing half of the array in each dimension.