started to support the viewer. Working on adding callbacks management

Former-commit-id: f24ea0f882

python/python.cpp

@@ -5,6 +5,7 @@
 
 extern void python_export_vector(py::module &);
 extern void python_export_igl(py::module &);
+extern void python_export_igl_viewer(py::module &);
 
 PYTHON_PLUGIN(igl) {
     py::init_threading();
@@ -12,6 +13,7 @@ PYTHON_PLUGIN(igl) {
 
     python_export_vector(m);
     python_export_igl(m);
+    python_export_igl_viewer(m);
 
     return m.ptr();
 }