use exec except of system() to start external viewer

src/utils/execmd.cpp

@@ -127,7 +127,7 @@ public:
     ~ExecCmdRsrc() {
 	if (!m_active || !m_parent)
 	    return;
-	LOGDEB0(("~ExecCmdRsrc: working\n"));
+	LOGDEB1(("~ExecCmdRsrc: working. mypid: %d\n", (int)getpid()));
 	int status;
 	if (m_parent->m_pid > 0) {
 	    LOGDEB(("ExecCmd: killing cmd\n"));

src/utils/execmd.h

@@ -199,6 +199,9 @@ class ExecCmd {
     // Child process code
     void dochild(const string &cmd, const list<string>& args, 
 		 bool has_input, bool has_output);
+    /* Copyconst and assignment private and forbidden */
+    ExecCmd(const ExecCmd &) {}
+    ExecCmd& operator=(const ExecCmd &) {return *this;};
 };