temporary commit for merge with previous change on laptop

- NEW : begin to add the class for solving two dimensional Poisson problem
- CHG : rename the class for solving matrix
Merge branch 'master' of https://github.com/lunzhy/SimCTM
Add contact and complete the consideration of boundary conditions in this version.

- ENH : enhance the class for boundary condition
- NEW : add the class for contact in domain of finite differential method. And the boundary conditions is set in SimpleONO in cases of contact and boundary vertex.