Add rig_band_changed function for customization of rig actions on each band

This takes user action to customize during build right now.

src/rig.c

@@ -1932,6 +1932,104 @@ static int twiddling(RIG *rig)
     RETURNFUNC2(0);
 }
 
+// Can customize during build
+// Eventually should improved this for external actions when
+// rigctld gets integrated as a service within Hamlib
+static int rig_band_changed(RIG *rig, hamlib_bandselect_t band)
+{
+    // Examples:
+    // rig_set_func(rig, RIG_VFO_CURR, RIG_FUNC_TUNER, 1);
+    // rig_set_func(rig, RIG_VFO_CURR, RIG_FUNC_TUNER, 0);
+    // value_t v;
+    // rig_set_ant(rig, RIG_VFO_CURR, 1, v);
+    switch (band)
+    {
+    case RIG_BANDSELECT_2200M:
+        break;
+
+    case RIG_BANDSELECT_600M:
+        break;
+
+    case RIG_BANDSELECT_160M:
+        break;
+
+    case RIG_BANDSELECT_80M:
+        break;
+
+    case RIG_BANDSELECT_60M:
+        break;
+
+    case RIG_BANDSELECT_40M:
+        break;
+
+    case RIG_BANDSELECT_30M:
+        break;
+
+    case RIG_BANDSELECT_20M:
+        break;
+
+    case RIG_BANDSELECT_17M:
+        break;
+
+    case RIG_BANDSELECT_15M:
+        break;
+
+    case RIG_BANDSELECT_12M:
+
+        break;
+
+    case RIG_BANDSELECT_10M:
+        break;
+
+    case RIG_BANDSELECT_6M:
+        break;
+
+    case RIG_BANDSELECT_WFM:
+        break;
+
+    case RIG_BANDSELECT_MW:
+        break;
+
+    case RIG_BANDSELECT_AIR:
+        break;
+
+    case RIG_BANDSELECT_2M:
+        break;
+
+    case RIG_BANDSELECT_1_25M:
+        break;
+
+    case RIG_BANDSELECT_70CM:
+        break;
+
+    case RIG_BANDSELECT_33CM:
+        break;
+
+    case RIG_BANDSELECT_23CM:
+        break;
+
+    case RIG_BANDSELECT_13CM:
+        break;
+
+    case RIG_BANDSELECT_9CM:
+        break;
+
+    case RIG_BANDSELECT_5CM:
+        break;
+
+    case RIG_BANDSELECT_3CM:
+        break;
+
+    case RIG_BANDSELECT_GEN:
+        break;
+
+    default:
+        rig_debug(RIG_DEBUG_ERR, "%s: Unknown band=%d\n", __func__, band);
+    }
+
+    return RIG_OK;
+}
+
 /**
  * \brief set the frequency of the target VFO
  * \param rig   The rig handle
@@ -1958,6 +2056,8 @@ int rig_set_freq(RIG *rig, vfo_t vfo, freq_t freq)
     int retcode;
     freq_t freq_new = freq;
     vfo_t vfo_save;
+    static int last_band = -1;
+    int curr_band;
 
     if (CHECK_RIG_ARG(rig))
     {
@@ -1965,9 +2065,21 @@ int rig_set_freq(RIG *rig, vfo_t vfo, freq_t freq)
         return -RIG_EINVAL;
     }
 
+    curr_band = rig_get_band(rig, freq, -1);
+
+    if (curr_band != last_band)
+    {
+        rig_debug(RIG_DEBUG_ERR, "%s: band changing to %s\n", __func__,
+                  rig_get_band_str(rig, curr_band, 0));
+        rig_band_changed(rig, curr_band);
+        last_band = curr_band;
+    }
+
     ELAPSED1;
     ENTERFUNC;
     LOCK(1);
+
+
 #if BUILTINFUNC
     rig_debug(RIG_DEBUG_VERBOSE, "%s called vfo=%s, freq=%.0f, called from %s\n",
               __func__,