Related to issue #563.

* spot/twaalgos/hoa.hh (create_alias_basis): New function.
* spot/twaalgos/hoa.cc (create_alias_basis): New function.
(print_hoa): Add support for option 'b' and create_alias_basis
in this case.
* bin/common_aoutput.cc, NEWS: Document -Hb.
* tests/core/readsave.test, tests/python/aliases.py: Add test cases.