Split up texture filtering properties of SMaterialLayer into MinFilter and MagFilter

You can	now set	the filter used	when scaling textures down and the filter used when scaling textures up separately.

src/client/content_cso.cpp

@@ -43,7 +43,8 @@ class SmokePuffCSO: public ClientSimpleObject
 			mat.Lighting = false;
 			mat.FogEnable = true;
 			mat.forEachTexture([] (video::SMaterialLayer &tex) {
-				tex.BilinearFilter = false;
+				tex.MinFilter = video::ETMINF_NEAREST;
+				tex.MagFilter = video::ETMAGF_NEAREST;
 			});
 		});
 		m_spritenode->setColor(video::SColor(255,0,0,0));