New version of GOLEM

[ajacquey]

Here is a list of improvements - new features which could the topic of a new GOLEM release version:

• Improve memory usage for the mechanics
• Direct solve for the plastic update
• Direct solve for Maxwell viscoelasticity
• Advection based on the entropy-production viscosity formulation
• Aperture update based on normal and shear stress on fault plane (Hannes)
• Reorganization of the materials
• Use automatic differentiation