EMI: Fix crash when restarting the game

ResidualVM's EMI patch installs a custom version of system_prefs.loadprefs
which maps config reads to GetResidualVMPreference() calls. The original
system_prefs.cfg is saved and used as source for default values. When
the custom loadprefs function is called a second time (i.e. when using
the New Game option in the main menu) any config read results in an
endless recursion.
EMI: Use parent sort order for attached actors

When drawing attached actors the engine uses the parent's sort order
plus one. This offset can move the attached actor behind a background
plane, for instance the chess board in the Lucre docks or Guybrush when
riding the manatee.
Merge pull request #831 from inguin/emi-attached-sort-order

EMI: Use parent sort order for attached actors
Merge pull request #818 from inguin/emi-new-game

EMI: Fix crash when restarting the game
GRIM: Fix broken overriding functions play and loadFile in NullPlayer
ANDROID: Remove unused htc_fail and shake_offset fields
ANDROID: Factor event pushing into pushEvent
ANDROID: Move event queueing out of backend
ANDROID: Remove force_redraw
wip