Option to change WiFi gain from web interface

code/espurna/config/general.h

@@ -229,6 +229,9 @@ PROGMEM const char* const custom_reset_string[] = {
 #define WIFI_RECONNECT_INTERVAL 120000      // If could not connect to WIFI, retry after this time in ms
 #define WIFI_MAX_NETWORKS       5           // Max number of WIFI connection configurations
 #define WIFI_AP_MODE            AP_MODE_ALONE
+#ifndef WIFI_GAIN
+#define WIFI_GAIN               0           // WiFi gain in dBm from 0 (normal) to 20.5 (max power and consumption)
+#endif
 
 // Optional hardcoded configuration (up to 2 different networks)
 //#define WIFI1_SSID              "..."

code/espurna/web.ino

@@ -594,6 +594,7 @@ void _wsStart(uint32_t client_id) {
         }
         #endif
 
+        root["wifiGain"] = getSetting("wifiGain", WIFI_GAIN).toFloat();
         root["maxNetworks"] = WIFI_MAX_NETWORKS;
         JsonArray& wifi = root.createNestedArray("wifi");
         for (byte i=0; i<WIFI_MAX_NETWORKS; i++) {

code/espurna/wifi.ino

@@ -50,6 +50,8 @@ bool createAP() {
 
 void wifiConfigure() {
 
+    WiFi.setOutputPower(getSetting("wifiGain", WIFI_GAIN).toFloat());
+
     jw.setHostname(getSetting("hostname").c_str());
     jw.setSoftAP(getSetting("hostname").c_str(), getSetting("adminPass", ADMIN_PASS).c_str());
     jw.setConnectTimeout(WIFI_CONNECT_TIMEOUT);

code/html/index.html

@@ -392,6 +392,19 @@
                                     <div class="pure-u-1 pure-u-sm-1-4"><input type="checkbox" name="alexaEnabled" tabindex="11" /></div>
                                 </div>
 
+                                <div class="pure-g">
+                                    <label class="pure-u-1 pure-u-md-1-4" for="wifiGain">WiFi gain</label>
+                                    <div class="pure-u-1 pure-u-md-3-4">
+                                        <select name="wifiGain" class="pure-u-3-4" tabindex="3">
+                                            <option value="0">Normal</a>
+                                            <option value="10">High</a>
+                                            <option value="20.5">Highest</a>
+                                        </select>
+                                    </div>
+                                    <div class="pure-u-0 pure-u-md-1-4">&nbsp;</div>
+                                    <div class="pure-u-1 pure-u-md-3-4 hint">More gain means better range but also more power consumption. Might not work equally on all devices.</div>
+                                </div>
+
                                 <div class="pure-g module module-ds module-dht">
                                     <label class="pure-u-1 pure-u-sm-1-4" for="tmpUnits">Temperature units</label>
                                     <div class="pure-u-1 pure-u-sm-1-4"><input type="radio" name="tmpUnits" tabindex="12" value="0"> Celsius (ºC)</input></div>