reworks because of 'tx_mode 2' and protocol issues

° added markers (GIO12, GPIO14) for logic analyzer debugging

° change UART initialisation
  - set RxFIFO full to 1 char, so we can detect active telegram on EMS-Bus
  - set RxTOT to 1 char for the same reason

° in ems_parseTelegram: ignore telegram if  emsRxStatus != EMS_RX_STATUS_IDLE
  because we missed to respond in a timely manner

° ems_tx_buffer is not void anymore, instead we return the Tx status
° extended the emsTxStatus
  - EMS_TX_WTD_TIMEOUT: timeout while waiting for echo of last Tx byte
    out telegram was ignored by the bus master, so the byte wasn't echoed
  - EMS_TX_BRK_DETECT:  BRK detected while sending the telegram
    bus master send us a break because of protocol violation

° add burnStarts, burnWorkMin and heatWorkMin to MQTT boiler message

TODO:
  + take care of ems_tx_buffer return code
  + accept direct telegram in ems_parse_telegram and do a proper acknowledge
  + split the heartbeat in static (version, IP-address) and dynamic (RSS etc)
  + change the hearbeat to a JSON structure so we can easier pick the uptime

src/ems.h

@@ -17,7 +17,6 @@
  *   ° for Rx, we use GPIO14
  *   ° for Tx, we use GPIO12
  */
-#define LOGICANALYZER
 #ifdef LOGICANALYZER
     #define RX_MARK_PIN 14
     #define TX_MARK_PIN 12
@@ -47,10 +46,10 @@
                                      GPIO_L(MARKERS_MASK);        \
                                 } while (0)
 #else
-    #define RX_PULSE(pulse)
-    #define TX_PULSE(pulse)
-    #define LA_PULSE(pulse)
-    #define INIT_MARKERS(void)
+    #define RX_PULSE(pulse) {}
+    #define TX_PULSE(pulse) {}
+    #define LA_PULSE(pulse) {}
+    #define INIT_MARKERS(void)  {}
 #endif
 
 #define EMS_ID_NONE 0x00 // used as a dest in broadcast messages and empty device IDs
@@ -104,6 +103,7 @@ typedef enum {
 } _EMS_RX_STATUS;
 
 typedef enum {
+    EMS_TX_STATUS_OK,  
     EMS_TX_STATUS_IDLE, // ready
     EMS_TX_STATUS_WAIT, // waiting for response from last Tx
     EMS_TX_WTD_TIMEOUT, // watchdog timeout during send