fix bugs: Update examples and docs for breaking changes in v3.0.0

- Change ClassName to NewClassName (mostly are BaseXXX to DevXXX) in docs/source/pages/general/advances/import_all_models.rst and examples/run_all_parameters.py
- Rename fit_func to obj_func in examples/applications/pytorch/linear_regression.py. Bug in issue 147 is fixed #147.