Implement remote command support.

- Defaut port is 7643 (totally arbitrary)

- Using RemoteCommandDMRG, each network can be enabled or disabled (net1 .. net5, xlx):
    ~ $ RemoteCommandDMRG 7643 disable net2
    M: 2021-03-20 11:48:40.494 Command sent: "disable net2" to port: 7643
    M: 2021-03-20 11:48:40.545 OK

- Using RemoteCommandDMRG, a connection status can be retrieved:
    ~ $ RemoteCommandDMRG 7643 status
    M: 2021-03-20 11:49:13.513 Command sent: "status" to port: 7643
    M: 2021-03-20 11:49:13.563 xlx:conn net1:conn net2:n/a net3:n/a net4:conn net5:n/a

A returned string is expected from the socket connection, this is why I did not reuse the MMDVMHost's RemoteCommand (unless MMDVMHost RemoteControl is modified as well).

The exit value can be used in scripting (also 1 if we didn't get any reply).

XLXVoice.cpp

@@ -195,7 +195,7 @@ void CXLXVoice::createVoice(const std::vector<std::string>& words)
 	for (unsigned int i = 0U; i < ambeLength; i += AMBE_LENGTH)
 		::memcpy(ambeData + i, SILENCE, AMBE_LENGTH);
 
-    // Put offset in for silence at the beginning
+	// Put offset in for silence at the beginning
 	unsigned int pos = SILENCE_LENGTH * AMBE_LENGTH;
 	for (std::vector<std::string>::const_iterator it = words.begin(); it != words.end(); ++it) {
 		if (m_positions.count(*it) > 0U) {
@@ -273,6 +273,19 @@ void CXLXVoice::createVoice(const std::vector<std::string>& words)
 	m_timer.start();
 }
 
+void CXLXVoice::reset()
+{
+	for (std::vector<CDMRData*>::iterator it = m_data.begin(); it != m_data.end(); ++it)
+		delete *it;
+
+	m_timer.stop();
+	m_status = XLXVS_NONE;
+	m_data.clear();
+	m_seqNo = 0U;
+	m_streamId = 0U;
+	m_sent = 0U;
+}
+
 bool CXLXVoice::read(CDMRData& data)
 {
 	if (m_status != XLXVS_SENDING)