Billing preferences

[novoselt]

• Changed the settings menu so that there is a top level Billing submenu similar to Preferences.
• Submenus are closed by default and only one is open at a time, selecting an item outside of them closes them.
• Added missing tiles for Upgrades and Payment Methods.
• Restyled the menu panel in collapsed/hidden mode: before icons were strangely off-center and submenus had arrows obscuring icons.
• The open/close behaviour is the same as with full size panels, only one is opened at a time.
• Simplified some code to avoid duplication and confusing different behaviour for similar elements when something is changed.
• There are new keys for translations, but translation was NOT done, I need some further advice on using SimpleLocalize.