Added an example for PyQt5 (#389)

* added pyqt5 example

* fixed example path on build

* improved pyqt example

* simplified example

examples/cpp/RemoteTerm/README.md

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+A simple example showing how to use QTermWidget to control and display a remote terminal.
+
+To run this example, you should: 
+1. Build client-side program. In my PC, I use 'apt-get' to install the QTermWidget library.
+2. Start the shell-srv.py with specific paramenters.This will expose a shell via socket.
+3. Start the client-side program from commandline with specific paramenters.
+
+Now you will get your own remote terminal work with QTermWidget.

examples/cpp/RemoteTerm/RemoteTerm.pro

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+#-------------------------------------------------
+#
+# Project created by QtCreator 2017-10-31T00:37:59
+#
+#-------------------------------------------------
+
+QT       += core gui network
+
+greaterThan(QT_MAJOR_VERSION, 4): QT += widgets
+
+TARGET = RemoteTerm
+TEMPLATE = app
+
+# The following define makes your compiler emit warnings if you use
+# any feature of Qt which as been marked as deprecated (the exact warnings
+# depend on your compiler). Please consult the documentation of the
+# deprecated API in order to know how to port your code away from it.
+DEFINES += QT_DEPRECATED_WARNINGS
+
+# You can also make your code fail to compile if you use deprecated APIs.
+# In order to do so, uncomment the following line.
+# You can also select to disable deprecated APIs only up to a certain version of Qt.
+#DEFINES += QT_DISABLE_DEPRECATED_BEFORE=0x060000    # disables all the APIs deprecated before Qt 6.0.0
+
+CONFIG += c++11
+
+SOURCES += \
+        main.cpp \
+    remoteterm.cpp
+
+HEADERS += \
+    remoteterm.h
+
+unix:!macx: LIBS += -lqtermwidget5

examples/cpp/RemoteTerm/main.cpp

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+#include "remoteterm.h"
+#include <QApplication>
+#include <QDebug>
+
+int main(int argc, char *argv[])
+{
+    QApplication a(argc, argv);
+    if(a.arguments().size() != 3){
+        qDebug() << "Example(client-side) for remote terminal of QTermWidget.";
+        qDebug() << QString("Usage: %1 ipaddr port").arg(a.arguments()[0]);
+        return 1;
+    }
+    QString ipaddr = a.arguments().at(1);
+    quint16 port = a.arguments().at(2).toUShort();
+    RemoteTerm w(ipaddr,port);
+    w.show();
+
+    return a.exec();
+}

examples/cpp/RemoteTerm/remoteterm.cpp

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+#include "remoteterm.h"
+#include <QTcpSocket>
+#include <QDebug>
+#include <unistd.h>
+
+RemoteTerm::RemoteTerm(const QString &ipaddr, quint16 port, QWidget *parent)
+    : QTermWidget(0,parent)
+{
+    socket = new QTcpSocket(this);
+    
+    // Write what we input to remote terminal via socket
+    connect(this, &RemoteTerm::sendData,[this](const char *data, int size){
+        this->socket->write(data, size);
+    });
+
+    // Read anything from remote terminal via socket and show it on widget.
+    connect(socket,&QTcpSocket::readyRead,[this](){
+        QByteArray data = socket->readAll();
+        write(this->getPtySlaveFd(), data.data(), data.size());
+    });
+    connect(socket, SIGNAL(error(QAbstractSocket::SocketError)),this,SLOT(atError()));
+
+    // Here we start an empty pty.
+    this->startTerminalTeletype();
+
+    socket->connectToHost(ipaddr, port);
+}
+
+void RemoteTerm::atError()
+{
+    qDebug() << socket->errorString();
+}

examples/cpp/RemoteTerm/remoteterm.h

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+#ifndef WIDGET_H
+#define WIDGET_H
+
+#include <qtermwidget5/qtermwidget.h>
+
+class QTcpSocket;
+
+class RemoteTerm : public QTermWidget
+{
+    Q_OBJECT
+public:
+    RemoteTerm(const QString &ipaddr, quint16 port, QWidget *parent = 0);
+public slots:
+     void atError();
+private:
+    QTcpSocket *socket;
+};
+
+#endif // WIDGET_H

examples/cpp/RemoteTerm/shell-srv.py

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+#!/usr/bin/env python
+
+import sys
+import os
+import socket
+import pty
+
+def usage(program):
+    print "Example(server-side) for remote terminal of QTermWidget."
+    print "Usage: %s ipaddr port" %program
+
+
+def main():
+    if len(sys.argv) != 3:
+        usage(sys.argv[0])
+        sys.exit(1)
+    s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
+    try:
+        s.bind((sys.argv[1], int(sys.argv[2])))
+        s.listen(0)
+        print "[+]Start Server."
+    except Exception as e:
+        print "[-]Error Happened: %s" %e.message
+        sys.exit(2)
+
+    while True:
+        c = s.accept()
+        os.dup2(c[0].fileno(), 0)
+        os.dup2(c[0].fileno(), 1)
+        os.dup2(c[0].fileno(), 2)
+
+        # It's important to use pty to spawn the shell.
+        pty.spawn("/bin/sh")
+        c[0].close()
+    
+if __name__ == "__main__":
+    main()