fix load obj texture filename when has any option

wrap/io_trimesh/import_obj.h

@@ -1049,10 +1049,10 @@ public:
 					std::string textureName;
 					if (tokens.size() < 2)
 						return false;
-          else if (tokens.size() == 2)
-            textureName = tokens[1]; //play it safe
-          else
-            textureName = line.substr(7); //get everything after "map_Kd "
+					else {
+						//the tex name is the last one (after any option)
+						textureName = tokens[tokens.size()-1];
+					}
 
 					currentMaterial.map_Kd=textureName;