export SVM::trainAuto to python #7224 (#8373)

* export SVM::trainAuto to python #7224

* workaround for ABI compatibility of SVM::trainAuto

* add parameter comments to new SVM::trainAuto function

* Export ParamGrid member variables

modules/ml/src/inner_functions.cpp

@@ -50,6 +50,10 @@ ParamGrid::ParamGrid(double _minVal, double _maxVal, double _logStep)
     logStep = std::max(_logStep, 1.);
 }
 
+Ptr<ParamGrid> ParamGrid::create(double minval, double maxval, double logstep) {
+  return makePtr<ParamGrid>(minval, maxval, logstep);
+}
+
 bool StatModel::empty() const { return !isTrained(); }
 
 int StatModel::getVarCount() const { return 0; }