Bug get basis functions

See merge request !319

Parallelhxt2gmsh

See merge request !318

* new occ/getBoundingBox and occ/getEntities to remove the need for some synchronizations when building large models

Parallelized the for loop with the longest running time of Hxt2Gmsh, reducing the running time by about 70%

Reduced the scope of critical sections when modifying vertex/element num.Make this operation thread-safe in the Gmodel class.

This allows to remesh fully discrete models, from 1D to 3D.