Layers

[chrisdugne]

remove

  -----------------------------------------
  -- layers (+ BG and stage)
  transversalBackLayer = display.newGroup(),
  transversalFrontLayer = display.newGroup(),
  hud = display.newGroup(),
  -----------------------------------------

use a set of back, flat, front layers

• for every scene
• a global set for cross-scenes
• game.camera still used for playground.scene