Add Observer. Remove functions from python side and add as observer of Problem. Add loads directions as functions. Minor changes.

Add interface for linear sovlers. Add macros definition at global level. Adapt modules to test the different linear solvers.

Move Vector3d interface to tboxw.i. Replace Pt by Vector3d in heat, katropton, mirrors and sph + python files. Node.pos and Results remains

Replaced std::vector by std::deque to avoir size estimation when building list of triplet for sparse matrix

Updt Mem stategy. Mem is now updated by Problem (aclled in Solver constructor) and MshDeformation. Add doc in MshData. Add test function in MshDeformation for test meshDeformation.py.

Add warning and Cpp11 check in CMake.  Corr most warnings. Add doc and thread init for MeshDeformation. Add utility folder to be sorted with all utilities.

(to be continued)

(see commit a52a375d)