Printhost: Persist upload path & start print checkbox (re-add lost code)

Fixes #1219
Fixes #1004
Fixes #1106
Fixes #1678

src/slic3r/GUI/PrintHostDialogs.hpp

@@ -33,6 +33,7 @@ public:
     boost::filesystem::path filename() const;
     bool start_print() const;
 
+    virtual void EndModal(int ret) override;
 private:
     wxTextCtrl *txt_filename;
     wxCheckBox *box_print;