Implemented a "Reset user profile" on the first page of the configuration

wizard if the wizard is opened from the menu. This allows one
to reinstall the bundled printer profile cleanly.

Fixed a bug when loading a config bundle as a config: The config bundle
should not be unpacked into the user profile directory.

xs/src/slic3r/GUI/Preset.hpp

@@ -116,6 +116,8 @@ public:
     PresetCollection(Preset::Type type, const std::vector<std::string> &keys);
     ~PresetCollection();
 
+    void            reset(bool delete_files);
+
     Preset::Type    type() const { return m_type; }
     std::string     name() const;
     const std::deque<Preset>& operator()() const { return m_presets; }