Merge branch 'warnings' into 'master'

Add platformio configuration; fix compilation warnings

See merge request Pwuts/Metertrekker2MQTT!2

SMRtoMQTT.ino

@@ -262,7 +262,7 @@ void parseTelegram(char* telegram)
               tmpValue = "";
               tmpValue.reserve(value.length()/2);
 
-              for (int i = 0; i < value.length()/2; i++) {
+              for (size_t i = 0; i < value.length()/2; i++) {
                 value.substring(i*2).getBytes(hexbuf, 3);
                 hexbuf[2] = 0;
 
@@ -331,7 +331,7 @@ void parseTelegram(char* telegram)
 
 metricDef* getMetricDef(const char* ident)
 {
-  for (int i = 0; i < sizeof(metricDefs)/sizeof(metricDefs[0]); i++)
+  for (size_t i = 0; i < sizeof(metricDefs)/sizeof(metricDefs[0]); i++)
   {
     if (strcmp(ident, metricDefs[i].ident) == 0) {
       return &metricDefs[i];

platformio.ini

@@ -0,0 +1,24 @@
+; PlatformIO Project Configuration File
+;
+;   Build options: build flags, source filter
+;   Upload options: custom upload port, speed and extra flags
+;   Library options: dependencies, extra library storages
+;   Advanced options: extra scripting
+;
+; Please visit documentation for the other options and examples
+; http://docs.platformio.org/page/projectconf.html
+
+[platformio]
+src_dir = .
+
+[env:default]
+platform = espressif8266
+board = d1_mini
+framework = arduino
+monitor_speed = 115200
+upload_speed = 1000000
+build_flags = -DMQTT_MAX_PACKET_SIZE=1024
+lib_ldf_mode = deep
+lib_deps =
+  PubSubClient
+