Fix issue 171 and 210, and change the name format of the pp3 files : now keep the output image extension in it, to avoid overwriting the pp3 file of an image with the same name, but with a different extension.

For consistency, the filename of the pp3 saved next to the output image in batch mode is modified in the same manner.

rtgui/options.h

@@ -95,6 +95,7 @@ class Options {
     Glib::ustring language;
     Glib::ustring theme;
     static Glib::ustring cacheBaseDir;
+    bool autoSuffix;
     bool saveParamsFile;
     bool saveParamsCache;
     PPLoadLocation paramsLoadLocation;