Strength reduction (#2817)

* input new files about slope stability

* input document of slope stability

* add something in Test file

* some changes in test file

* some changes in test file

* some changes in test and prj file

* some changes in input files

* [T/MCAS] Relax nonlinear solver tols. Formatting.

* [T] Reformatting file.

* Add somethings in input files

* some changes in slope files

* Cleanup. Set ctest to fail.

Co-authored-by: tengfei <dengtenfei2016@hotmail.com>
Co-authored-by: Dmitri Naumov <github@naumov.de>