Add a scripting mode to GPClient (#110)

GPClient/vpn_json.cpp

@@ -0,0 +1,24 @@
+#include "vpn_json.h"
+#include <QTextStream> 
+#include <QJsonDocument>
+#include <QJsonObject>
+#include <QJsonArray>
+
+void VpnJson::connect(const QString &preferredServer, const QList<QString> &servers, const QString &username, const QString &passwd, const QString &extraArgs) {
+    QJsonArray sl;
+    for (const QString &srv : servers) {
+      sl.push_back(QJsonValue(srv));
+    }
+    QJsonObject j;
+    j["server"] = preferredServer;
+    j["availableServers"] = sl;
+    j["cookie"] = passwd;
+    QTextStream(stdout) << QJsonDocument(j).toJson(QJsonDocument::Compact) << "\n";
+    emit connected();
+}
+
+void VpnJson::disconnect() { /* nop */ }
+
+int VpnJson::status() {
+    return 4; // disconnected
+}