Fixed compiler warnings

tools/python/src/basic.cpp

@@ -19,7 +19,7 @@ std::shared_ptr<std::vector<double> > array_from_object(py::object obj)
     try {
         long nr = obj.cast<long>();
         return std::make_shared<std::vector<double>>(nr);
-    } catch (py::cast_error &e) {
+    } catch (py::cast_error&) {
         py::list li = obj.cast<py::list>();
         const long nr = len(li);
         auto temp = std::make_shared<std::vector<double>>(nr);

tools/python/src/svm_struct.cpp

@@ -56,7 +56,7 @@ public:
         try {
             loss = t[0].cast<scalar_type>();
             psi = t[1].cast<feature_vector_type&>();
-        } catch(py::cast_error &e) {
+        } catch(py::cast_error&) {
             psi = t[0].cast<feature_vector_type&>();
             loss = t[1].cast<scalar_type>();
        }

tools/python/src/vector.cpp

@@ -59,7 +59,7 @@ std::shared_ptr<cv> cv_from_object(py::object obj)
         auto temp = std::make_shared<cv>(nr);
         *temp = 0;
         return temp;
-    } catch(py::cast_error &e) {
+    } catch(py::cast_error&) {
         py::list li = obj.cast<py::list>();
         const long nr = len(obj);
         auto temp = std::make_shared<cv>(nr);