Fixed LAYER_NUM usage in the specctra code.

A specctra layer is not a LAYER_NUM, so that's probably why it was difficult to use.

pcbnew/specctra.cpp

@@ -99,7 +99,7 @@ void SPECCTRA_DB::buildLayerMaps( BOARD* aBoard )
 
 int SPECCTRA_DB::findLayerName( const std::string& aLayerName ) const
 {
-    for( LAYER_NUM i=FIRST_LAYER;  i<int(layerIds.size());  ++i )
+    for( int i=0;  i < int(layerIds.size());  ++i )
     {
         if( 0 == aLayerName.compare( layerIds[i] ) )
             return i;

pcbnew/specctra.h

@@ -3743,7 +3743,7 @@ class SPECCTRA_DB : public SPECCTRA_LEXER
      *  or delete it.
      */
     PADSTACK* makeVia( int aCopperDiameter, int aDrillDiameter,
-                       LAYER_NUM aTopLayer, LAYER_NUM aBotLayer );
+                       int aTopLayer, int aBotLayer );
 
     /**
      * Function makeVia

pcbnew/specctra_export.cpp

@@ -1851,7 +1851,7 @@ void SPECCTRA_DB::FromBOARD( BOARD* aBoard ) throw( IO_ERROR )
                 wire->wire_type = T_protect;    // @todo, this should be configurable
 
                 LAYER_NUM kiLayer  = track->GetLayer();
-                LAYER_NUM pcbLayer = kicadLayer2pcb[kiLayer];
+                int pcbLayer = kicadLayer2pcb[kiLayer];
 
                 path = new PATH( wire );
 

pcbnew/specctra_import.cpp

@@ -224,7 +224,7 @@ static wxPoint mapPt( const POINT& aPoint, UNIT_RES* aResolution )
 
 TRACK* SPECCTRA_DB::makeTRACK( PATH* aPath, int aPointIndex, int aNetcode ) throw( IO_ERROR )
 {
-    LAYER_NUM layerNdx = findLayerName( aPath->layer_id );
+    int layerNdx = findLayerName( aPath->layer_id );
 
     if( layerNdx == -1 )
     {