Services

[topisani]

• Rename create_ functions to make_
• Let the Application constructor use Service::make_default by default
• Let the Application constructor take factories in any order
• Split UIManager into GraphicsManager and UIManager
  • UIManager handles the user interface state, i.e. the currently selected channel, the current screen (as a ScreenEnum only) and the state of the octave buttons
  • GraphicsManager Handles the actual drawing, mapping ScreenEnums to Screens etc.