started using QSettings, some refactoring (rename)

. QSettings saving and restoring window state and position
. renamed save/load functions
changed ui load/save settings, using QSettings

. new ways to load/save settings: restore last session, open, save,
export
. QSettings to save preferences and params
. use last used directory at QFileDialog
. deprecated previous load/save params
. fixed estimated necessary space at user order
. fixed current_network when removing last one
remove/reset stations when user ordering

. ui buttons to remove and reset stations list (user order)
. fixed estimate_necessary_space
workaround for QSettings on linux

because native format on linux is iniformat
. detects if running on linux
. save_settings with 3 statements to save diferently on linux
. open from file use a different method on linux