Revert "Fixes bugs produced by last commit."

This reverts commit 2b7a5c0ffe1f17b021c8d2f5bd58ca7220cd26c5.
Revert "Substitutes all DIRECTIONS['dir'] by DIR_dir."

This reverts commit 6465e13d8ce35f4006d6621b2c65d126d4381158.
Revert "Updates the indentation to better comply the PEP-8. Some changes remains to be done."

This reverts commit fa899410f173fe76915e25f0bc2950b4f680636b.