core.tab: consistent return value in get_selection()
simplify sanitizing of settings and core.shared module
settingobject: remove complexity of shorten_title setting
removed compatibility for "hidden_filter" option being a regex
renamed container.settingobject to container.settings

ranger.container.settingobject.SettingObject ->
ranger.container.settings.Settings

ranger.container.settingobject.LocalSettingObject ->
ranger.container.settings.LocalSettings

This is for more conformity.  No other class is called *Object.