Remove wifi distance calculation

code/espurna/wifi.ino

@@ -330,11 +330,6 @@ String getNetwork() {
     return WiFi.SSID();
 }
 
-double wifiDistance(int rssi) {
-    double exponent = (double) (WIFI_RSSI_1M - rssi) / WIFI_PROPAGATION_CONST / 10.0;
-    return round(pow(10, exponent));
-}
-
 bool wifiConnected() {
     return jw.connected();
 }

code/espurna/ws.ino

@@ -220,7 +220,6 @@ void _wsUpdate(JsonObject& root) {
     root["heap"] = getFreeHeap();
     root["uptime"] = getUptime();
     root["rssi"] = WiFi.RSSI();
-    root["distance"] = wifiDistance(WiFi.RSSI());
     #if NTP_SUPPORT
         if (ntpSynced()) root["now"] = now();
     #endif

code/html/index.html

@@ -199,7 +199,7 @@
                                     <div class="pure-u-11-24 pure-u-lg-17-24"><span class="right" name="channel"></span></div>
 
                                     <div class="pure-u-1-2 pure-u-lg-1-4">RSSI</div>
-                                    <div class="pure-u-11-24 pure-u-lg-17-24"><span class="right" name="rssi"></span> (<span name="distance" post="m"></span>)</div>
+                                    <div class="pure-u-11-24 pure-u-lg-17-24"><span class="right" name="rssi"></span></div>
 
                                     <div class="pure-u-1-2 pure-u-lg-1-4">IP</div>
                                     <div class="pure-u-11-24 pure-u-lg-17-24"><span class="right" name="deviceip"></span></div>