Pcbnew, apparence control: add missing control of layer footprint confict

the selection of color and visibility of LAYER_CONFLICTS_SHADOW was missing.

pcbnew/pcb_draw_panel_gal.cpp

@@ -651,8 +651,8 @@ void PCB_DRAW_PANEL_GAL::setDefaultLayerDeps()
 
     m_view->SetLayerTarget( LAYER_ANCHOR, KIGFX::TARGET_NONCACHED );
     m_view->SetLayerDisplayOnly( LAYER_ANCHOR );
-    
-    m_view->SetLayerTarget( LAYER_CONFLICTS_SHADOW, KIGFX::TARGET_OVERLAY );
+
+    m_view->SetLayerTarget( LAYER_CONFLICTS_SHADOW, KIGFX::TARGET_NONCACHED );
 
     m_view->SetLayerDisplayOnly( LAYER_LOCKED_ITEM_SHADOW );
     m_view->SetLayerDisplayOnly( LAYER_CONFLICTS_SHADOW );

pcbnew/widgets/appearance_controls.cpp

@@ -345,6 +345,7 @@ const APPEARANCE_CONTROLS::APPEARANCE_SETTING APPEARANCE_CONTROLS::s_objectSetti
     RR( _HKI( "DRC Exclusions" ),     LAYER_DRC_EXCLUSION,      _HKI( "DRC violations which have been individually excluded" ) ),
     RR( _HKI( "Anchors" ),            LAYER_ANCHOR,             _HKI( "Show footprint and text origins as a cross" ) ),
     RR( _HKI( "Locked Item Shadow" ), LAYER_LOCKED_ITEM_SHADOW, _HKI( "Show a shadow marker on locked items" ) ),
+    RR( _HKI( "Conflict Fp Shadow" ), LAYER_CONFLICTS_SHADOW,   _HKI( "Show a shadow marker on conflicting footprints" ) ),
     RR( _HKI( "Drawing Sheet" ),      LAYER_DRAWINGSHEET,       _HKI( "Show drawing sheet borders and title block" ) ),
     RR( _HKI( "Grid" ),               LAYER_GRID,               _HKI( "Show the (x,y) grid dots" ) )
 };