fix warnings

Former-commit-id: 2d7e665bed2543ccc29e6450f4036a661e308f9f

tutorial/403_BoundedBiharmonicWeights/main.cpp

@@ -142,7 +142,7 @@ int main(int argc, char *argv[])
   bbw_data.verbosity = 2;
   if(!igl::bbw(V,T,b,bc,bbw_data,W))
   {
-    return false;
+    return EXIT_FAILURE;
   }
 
   //MatrixXd Vsurf = V.topLeftCorner(F.maxCoeff()+1,V.cols());
@@ -176,4 +176,5 @@ int main(int argc, char *argv[])
     "Press ',' to show previous weight function."<<endl<<
     "Press [space] to toggle animation."<<endl;
   viewer.launch();
+  return EXIT_SUCCESS;
 }

tutorial/406_FastAutomaticSkinningTransformations/main.cpp

@@ -82,6 +82,8 @@ bool pre_draw(igl::viewer::Viewer & viewer)
     }
     switch(mode)
     {
+      default:
+        assert("unknown mode");
       case MODE_TYPE_ARAP:
         igl::arap_solve(bc,arap_data,U);
         break;

tutorial/608_LIM/main.cpp

@@ -27,7 +27,7 @@ bool key_down(igl::viewer::Viewer& viewer,unsigned char key,int modifier)
   using namespace std;
   using namespace Eigen;
 
-  if(key >= '0' && key <= '5' || key == 'B')
+  if((key >= '0' && key <= '5') || key == 'B')
   {
     // compute locally injective map
     Energy energy = Energy(key - '1');

tutorial/712_DataSmoothing/main.cpp

@@ -95,6 +95,7 @@ int main(int argc, char * argv[])
         Eigen::MatrixXd colors;
         igl::jet(*z, true, colors);
         viewer.data.set_colors(colors);
+        return true;
     };
     std::cout << R"(Usage:
 1  Show original function