Add elecraft_get_vfo_tq to take advantage of K4's new TQ command

https://github.com/Hamlib/Hamlib/issues/863

rigs/kenwood/elecraft.c

@@ -471,3 +471,33 @@ int elecraft_get_firmware_revision_level(RIG *rig, const char *cmd,
 
     return RIG_OK;
 }
+
+//  FR;FT;TQ; is faster than IF;
+//  Works on K4
+int elecraft_get_vfo_tq(RIG *rig, vfo_t *vfo)
+{
+    int retval;
+    int fr,ft,tx;
+    char cmdbuf[10];
+    char splitbuf[12];
+    snprintf(cmdbuf,sizeof(cmdbuf),"FR;FT;TQ;");
+    memset(splitbuf,0,sizeof(splitbuf));
+    retval = kenwood_safe_transaction(rig, cmdbuf, splitbuf, 9, 12);
+
+    if (retval != RIG_OK)
+    {
+        RETURNFUNC(retval);
+    }
+
+    if(sscanf(splitbuf, "FT%1d;FT%1d;TQ%1d", &fr, &ft, &tx) == 3)
+    {
+        RETURNFUNC(RIG_OK);
+    }
+    else {
+        rig_debug(RIG_DEBUG_ERR, "%s: unable to parse '%s'\n", __func__, splitbuf);
+    }
+    if (tx) *vfo = ft;
+    else *vfo = fr;
+    RETURNFUNC(RIG_OK);
+}
+

rigs/kenwood/elecraft.h

@@ -132,5 +132,7 @@ int elecraft_open(RIG *rig);
 		{ 103, 60 }, \
 	} }
 
+// K4 is the only we know that has this as of 2021-11-09
+int elecraft_get_vfo_tq(RIG *rig, vfo_t *vfo);
 
 #endif /* _ELECRAFT_H */

rigs/kenwood/k3.c

@@ -484,7 +484,7 @@ const struct rig_caps k4_caps =
     RIG_MODEL(RIG_MODEL_K4),
     .model_name =       "K4",
     .mfg_name =     "Elecraft",
-    .version =      BACKEND_VER ".17",
+    .version =      BACKEND_VER ".18",
     .copyright =        "LGPL",
     .status =       RIG_STATUS_STABLE,
     .rig_type =     RIG_TYPE_TRANSCEIVER,
@@ -597,7 +597,7 @@ const struct rig_caps k4_caps =
     .set_mode =     k3_set_mode,
     .get_mode =     k3_get_mode,
     .set_vfo =      k3_set_vfo,
-    .get_vfo =      k3_get_vfo,
+    .get_vfo =      elecraft_get_vfo_tq,
     .set_split_mode =   k3_set_split_mode,
     .get_split_mode =   k3_get_split_mode,
     .set_split_vfo =    kenwood_set_split_vfo,