Revert "implement more accurate porosity calculation..." (temporary required in order to revert 915fd94606af6 without conflict)"

This reverts commit 9e512fd50083292f5c04e05d10d59d66654f978d.
Revert "fix typos and indents; cut long lines.. - please no formatting commits (+there is nothing wrong in long lines). Please reapply the documentation part."

This reverts commit 915fd94606af66d0d7946ed9cbf0c7bb25ee040b.