Application info: Checking if directory exists (swift version exists) plus fixes in property functions

src/blackmisc/applicationinfo.h

@@ -47,6 +47,7 @@ namespace BlackMisc
             IndexApplicationDataPath,
             IndexCompileInfo,
             IndexExecutablePath,
+            IndexExecutablePathExisting,
             IndexPlatformInfo,
             IndexProcessInfo,
             IndexVersionString,
@@ -74,6 +75,11 @@ namespace BlackMisc
         //! Get executable path.
         const QString &getExecutablePath() const { return m_exePath; }
 
+        //! Is the executable path existing?
+        //! \remark this indicates if the swift version is still existing
+        //! \remark file check, relatively slow
+        bool isExecutablePathExisting() const;
+
         //! Set application data dir
         //! \remark rootdir of settings, cache and logs
         void setApplicationDataDirectory(const QString &appDataDir) { m_applicationDataDir = appDataDir; }