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

Actually, if you put a CAST after a relation (!= ``is`` or ``is_instance_of``),
the checker raises an error saying that the etype (inside the CAST) must be
after a ``is`` or ``is_instance_of`` relation. In fact the CAST case was tested too late.

This allow to use CAST outside the selection section, so:
Closes #79232

Added tag rql-version-0.32.0, rql-debian-version-0.32.0-1, rql-centos-version-0.32.0-1 for changeset 843843e76fac

Allow rql to work with yapps 2.2.0 which is properly released on pypi, and remove the custom dependency link for it.

Closes #124962
Closes #245540

Allow multiple (non "=") operators for uid variables.

It just degrades the readability for no apparent benefit.

Closes #190394.