added command queue

+ command queue
+ feedback from inverter for actual power limit via InfoCmd -> SystemConfigPara (0x05)
+ REST API will enqueue a new info command
+ change in power limit will enqueue infocm to get actual power limit
+ actual power limit is available under mqtt topic <TOPIC>/<NAME>/ch0/PowerLimit ALWAYS in percent
+ Firmware information will be requested automatically up on start of dtu

tools/esp8266/hmSystem.h

@@ -19,13 +19,10 @@ class HmSystem {
         RadioType Radio;
         typedef BUFFER BufferType;
         BufferType BufCtrl;
-        InfoCmdType NextInfoCmd; // For cmd-queue FIFO with one place
-        InfoCmdType InfoCmd;     // For cmd-queue FIFO with one place
         //DevControlCmdType DevControlCmd;        
 
         HmSystem() {
             mNumInv = 0;
-            InfoCmd = RealTimeRunData_Debug; // default case
         }
         ~HmSystem() {
             // TODO: cleanup