[Server] Use Project selection color in GetPrint for 2.18

QGIS Server uses QgsMapRenderer and not QgsMapSettings to configure maps
rendering, and color selection was not transmitted between QgsMapRenderer and
QgsMapSettings and between mapSettings and jobMapSettings in QgsMapComposer.

This commit completes:
* [Server] Reactivate the capability to print selection with Server 2.18 3d0f1b6
* [Server] Read and activate selection color 79a212e

src/core/composer/qgscomposermap.cpp

@@ -231,6 +231,7 @@ QgsMapSettings QgsComposerMap::mapSettings( const QgsRectangle& extent, QSizeF s
   jobMapSettings.setCrsTransformEnabled( ms.hasCrsTransformEnabled() );
   jobMapSettings.setFlags( ms.flags() );
   jobMapSettings.setFlag( QgsMapSettings::DrawSelection, mDrawSelection );
+  jobMapSettings.setSelectionColor( ms.selectionColor() );
   jobMapSettings.setFlag( QgsMapSettings::RenderPartialOutput, false );
 
   if ( mComposition->plotStyle() == QgsComposition::Print ||

src/core/qgsmaprenderer.cpp

@@ -1268,6 +1268,15 @@ const QgsMapSettings& QgsMapRenderer::mapSettings()
   mMapSettings.setCrsTransformEnabled( hasCrsTransformEnabled() );
   mMapSettings.setDestinationCrs( destinationCrs() );
   mMapSettings.setMapUnits( mapUnits() );
+
+  // set selection color
+  QgsProject* prj = QgsProject::instance();
+  int myRed = prj->readNumEntry( "Gui", "/SelectionColorRedPart", 255 );
+  int myGreen = prj->readNumEntry( "Gui", "/SelectionColorGreenPart", 255 );
+  int myBlue = prj->readNumEntry( "Gui", "/SelectionColorBluePart", 0 );
+  int myAlpha = prj->readNumEntry( "Gui", "/SelectionColorAlphaPart", 255 );
+  mMapSettings.setSelectionColor( QColor( myRed, myGreen, myBlue, myAlpha ) );
+
   return mMapSettings;
 }