Modifying MIC3D_SPHERES

Deleting useless function mvp_3 in util.h.
Overloading mvp and replacing mvp_2 & mvp_3.

It was replaced by write_log, now it is a private micropp function and
it is called after each homogenization step.

Adding homogenize parameter to avoid FE calculations in ONE-WAY
micro-problems for internal iterations of the macro-scale.

Separating homogenize in : homogenize_task and homogenize
gpu_id is global and selected only in the constructor