Fixed portability issues and added CPack packaging support.

Now STA works as a portable application only in custom paths. If installed into a default system directory, where config and data files can't be written in the folder with the application executable, STA works as a standalone app. Appropriate changes have been applied to storing profiles of default params as well.
Also PORTABLE_VERSION CMake parameter has been added to control whether to build the portable version. If disabled, the setting are never stored in the folder with the program even if that's a custom path.
(Use cmake ... -D PORTABLE_VERSION={ON/OFF} ... when building)

Added CPack packaging support: see https://github.com/4lex4/scantailor-libs-build#packaging for more info.

Also now on installing on Linux, scantailor project mime-type is registered and STA is added into start menu.

Author: 4lex4

Application.cpp

@@ -31,10 +31,12 @@
 #include "Application.h"
 #include "OutOfMemoryHandler.h"
 #include <config.h>
-#include <QtCore/QDir>
+#include <QDir>
+#include <QTemporaryDir>
 
 Application::Application(int& argc, char** argv) : QApplication(argc, argv), m_currentLocale("en") {
     initTranslations();
+    initPortableVersion();
 }
 
 bool Application::notify(QObject* receiver, QEvent* e) {
@@ -83,7 +85,7 @@ void Application::initTranslations() {
 
     const QStringList language_file_filter("scantailor_*.qm");
     for (const QString& path : translation_dirs) {
-        QDir dir(QDir::cleanPath(applicationDirPath() + '/' + path));
+        QDir dir = (QDir::isAbsolutePath(path)) ? QDir(path) : QDir::cleanPath(applicationDirPath() + '/' + path);
         if (dir.exists()) {
             QStringList translationFileNames = QDir(dir.path()).entryList(language_file_filter);
             for (const QString& fileName : translationFileNames) {
@@ -96,3 +98,24 @@ void Application::initTranslations() {
         }
     }
 }
+
+void Application::initPortableVersion() {
+    const QString portableConfigDirName = QString::fromUtf8(PORTABLE_CONFIG_DIR);
+    if (portableConfigDirName.isEmpty()) {
+        return;
+    }
+
+    const QDir portableConfigPath(applicationDirPath() + '/' + portableConfigDirName);
+    if ((portableConfigPath.exists() && QTemporaryDir(portableConfigPath.absolutePath()).isValid())
+        || (!portableConfigPath.exists() && portableConfigPath.mkpath("."))) {
+        m_portableConfigPath = portableConfigPath.absolutePath();
+    }
+}
+
+bool Application::isPortableVersion() const {
+    return !m_portableConfigPath.isNull();
+}
+
+const QString& Application::getPortableConfigPath() const {
+    return m_portableConfigPath;
+}

Application.h

@@ -22,7 +22,6 @@
 #include <QApplication>
 #include <QTimer>
 #include <QtCore/QTranslator>
-#include "ui_MainWindow.h"
 #include "FilterUiInterface.h"
 #include "BackgroundTask.h"
 #include "OutputFileNameGenerator.h"
@@ -40,13 +39,20 @@ class Application : public QApplication {
 
     std::list<QString> getLanguagesList() const;
 
+    bool isPortableVersion() const;
+
+    const QString& getPortableConfigPath() const;
+
 private:
     void initTranslations();
 
+    void initPortableVersion();
+
 
     QTranslator m_translator;
     QString m_currentLocale;
     std::map<QString, QString> m_translationsMap;
+    QString m_portableConfigPath;
 };