Officially update to v1.1

Build 20180712

1. Discontinous constant,linear and quadratic element is supported
2. Exact analytical integrations for all elements is added
3. Anisotropic properties is supported
4. Key calculations are acclerated by Cython (40X improvements)
5. Thanks to exact integration. The Code structure is simplifed and updated.
   -BEM_2D is splitted into BEM_2D,BEM_2D_Mesh and BEM_2D_PostProcess
   -Matrix assembler for different elements is unified.
6. The visulization tools are improved and updated.
7. Serveral examples are added and verified with FEM Solution.