Better Python detection using windows registry (Win32)

Propose to install python if missing (Win32)

src/searchengine.h

@@ -70,6 +70,9 @@ private:
   QList<QPointer<SearchTab> > all_tab; // To store all tabs
   const SearchCategories full_cat_names;
   GUI *parent;
+#ifdef Q_WS_WIN
+  bool has_python;
+#endif
 
 public:
   SearchEngine(GUI *parent, Bittorrent *BTSession);
@@ -127,7 +130,10 @@ protected slots:
   void fillCatCombobox();
   void searchTextEdited(QString);
 #ifdef Q_WS_WIN
-  void checkForPythonExe();
+  bool addPythonPathToEnv();
+  void installPython();
+  void pythonDownloadSuccess(QString url, QString file_path);
+  void pythonDownloadFailure(QString url, QString error);
 #endif
 };