Added Kaco inverter implementation

- Added Kaco inverter implementation
- Small refactoring
- Added release inverter power signal for simultaneous start of the
  inverters

PLC/POUs/Sunspec/Refu/U_SUNSPEC_ERROR.TcDUT

@@ -0,0 +1,28 @@
+<?xml version="1.0" encoding="utf-8"?>
+<TcPlcObject Version="1.1.0.1" ProductVersion="3.1.4026.12">
+  <DUT Name="U_SUNSPEC_ERROR" Id="{4000836c-9d7f-470c-9b50-f6d22b3eac05}">
+    <Declaration><![CDATA[TYPE U_SUNSPEC_ERROR :
+UNION
+	xGroundFault : BOOL;
+	xDCOverVoltage : BOOL;
+	xACDisconnected : BOOL;
+	xDCDisconnected : BOOL;
+	xGridDisconnected : BOOL;
+	xCabinetOpen : BOOL;
+	xManualShutdown : BOOL;
+	xOverTemp : BOOL;
+	xOverFrequency : BOOL;
+	xUnderFrequency : BOOL;
+	xACOverVoltage : BOOL;
+	xACUnderVoltage : BOOL;
+	xBlownStringFuse : BOOL;
+	xUnderTemp : BOOL;
+	xMemoryLoss : BOOL;
+	xHWTestFailure : BOOL;
+	xOtherAlarm : BOOL;
+	xOtherWarning : BOOL;
+END_UNION
+END_TYPE
+]]></Declaration>
+  </DUT>
+</TcPlcObject>