Closes #298337

Fix regression introduced by switch to dh_python2: it reads our
egg-info/requires.txt to try and guess package dependencies.  This
generates a broken dependency on nonexistent "python-yapps" (instead of
yapps2-runtime) and an unnecessary one on python-logilab-constraint (we
use gecode).

Use subprocess instead of os.system.

Move sources to a 'rql' subdirectory, drop the NO_SETUPTOOLS code path
(essentially rewriting all of setup.py).  This avoids a conflict between
our parser.py and the stdlib when running setup.py.  Closes #278637.

Implicit relative imports no longer work.

Popen's stdout is a byte stream.

Instead of sorting and comparing lists of dicts, use assertCountEqual.

Requires python >= 2.6.

Use six-provided "types" whenever possible.

Requires python >= 2.6.

Requires python >= 2.6.

python 3 removed the raise syntax with 3 expressions.

We no longer support python 2.5.

All supported python versions have it builtin.

Added tag rql-version-0.33.0, rql-debian-version-0.33.0-1, rql-centos-version-0.33.0-1 for changeset 659a6b26eedc