Revert "Extract constants for genes in embryology"

This reverts commit 4f26e3c51e9c6e23240efa9408af606f8906cdc8.
Revert "Add one gene to chromosomes"

This reverts commit 9846a4f7ad097886398093ed70ed7d4dfe85e9fd.
Revert "New body plan: snake-like bodies"

This reverts commit 99047971d19f959c48a37f6fd38bbc2c861e46ff.