Allow to disable the check of memory consumption

[Algiane]

Maximal available memory is evaluated and stored in memMax field of the mesh. Then, at each allocation/unallocation, Mmg computes the used memory and check that it doesn't overflow the maximal authorized one.

It is useful to keep local computer running smoothly or to ensure that Mmg will save a mesh if it fails due to lack of memory.

But it can also be annoying:

• the system optimizes memory allocation, thus, Mmg checks may detect a lack of memory when in fact it is possible to end the remeshing process
• inside ParMmg it has no interests:
  • it is almost never possible to save the mesh (because groups merging step needs available memory)
  • it forces to compute and distribute remaining memory between the each Mmg process and ParMmg which is tricky, source of errors (erroneous detection of lack of memory) and quite wordy

Allowing disabling of memory checks in Mmg can be useful.