[CL] Encapsulated into ChemicalSystem

Fix some of the CppCheck warnings.

Split shifting coordinates and creating nodes.
The implemention uses more memory but avoids a lot
of shifting operations.

This needs some changes in other files, too.

CppCheck constness

Two corrections in MPL classes

Added bulk moduli computation to CreepBGRa and LinearElasticOrthotropic.

Add GitLab CI config

Rename s.t. declaration and definition are equal.

Install clcache with:

pip install git+https://github.com/frerich/clcache.git@cae73d8255d78db8ba11e23c51fd2c9a89e7475b

Use env var CTEST_PARALLEL_LEVEL instead.