Technical pre-release for the DFK code testing on HPC servers

This is the technical (testing) release of the DFK code, which is still under further active development. In its current version, the code can simulate multiple cracking processes in $Al_2O_3$ ceramics composites with rGO inclusions in the presence of growing macroscopic cracks.
The folder with the PCC complex examples contains two PCCs containing 1000 and 10000 3-cells.