Fix editing of function arguments; Show value instead of stored expression in...

Fix editing of function arguments; Show value instead of stored expression in variable edit dialog for approximate variables with expression without uncertainty; Make closing of application with Escape key optional (enabled by default if system tray icon is used); Add temporary option to unknown edit dialog; Disable editing of name for x, y, and z variables; Fix "E" at end of longitude; Improve labels for objects without specific title; Fix compatibility with old GTK versions; Reduce height of edit function dialog; Fix width of min and max field in function argument dialog; Update ChangeLog; Increment version number