Remove GModelFactory

See merge request gmsh/gmsh!48

- report boundary recovery issues with new boundary reciver code

new options to fine-tune number of threads:

See merge request gmsh/gmsh!47

Mesh.NumThreads : set/get number of threads
Mesh.MaxNumThreads1D : overrides number of threads for 1D meshing (if != 0 ; 0 by default)
Mesh.MaxNumThreads2D : overrides number of threads for 2D meshing (if != 0 ; 0 by default)
Mesh.MaxNumThreads3D : overrides number of threads for 3D meshing (if != 0 ; 0 by default)

methods in functionSpace should be constant

See merge request gmsh/gmsh!45

fullVector and complex values

See merge request gmsh/gmsh!46

fullVector<>::norm() is wrong for complex values -> add complex specialisation (keep inline and double version for performances).
Specialisation of fullVector<>::axpy for complex values.

- only apply BooleanFragments to highest dim shapes in "Coherence"

similar to translate+rotate extrusion, with thrusections (but cannot use structured grid, of course)

operator equal for STensor33

See merge request gmsh/gmsh!44

add equal tensor operations

See merge request gmsh/gmsh!43

new ServerAction attribute to reset onelab variables: e.g. ServerAction "Reset" or SeverAction "Reset var1 var2".

(ServerAction "Reset" replaces GmshOption "Reset", which is still supported but deprecated)

- create compounds when doing transformations (translate, rotate, ...) so that we don't duplicate internal boundaries
- reset STL parameters to previous values