Add support for sendCOMM method

Credits go to user @angelsware, I just did a copy/paste from #120

xpcPlugin/DataManager.cpp

@@ -19,6 +19,7 @@
 
 #include "XPLMDataAccess.h"
 #include "XPLMGraphics.h"
+#include "XPLMUtilities.h"
 
 #include <algorithm>
 #include <cmath>
@@ -791,6 +792,21 @@ namespace XPC
 		Set(DREF_FlapActual, value);
 	}
 
+	void DataManager::Execute(const std::string& comm)
+	{
+		Log::FormatLine(LOG_INFO, "DMAN", "Executing command (value:%s)", comm.c_str());
+
+ 		XPLMCommandRef xcref = XPLMFindCommand(comm.c_str());
+		if (!xcref)
+		{
+			// COMM does not exist
+			Log::FormatLine(LOG_ERROR, "DMAN", "ERROR: invalid COMM %s", comm.c_str());
+			return;
+		}
+
+ 		XPLMCommandOnce(xcref);
+	}
+
 	float DataManager::GetDefaultValue()
 	{
 		return -998.0F;