when types are actually yams schema instead of bare string, one ended up with:

  File "/usr/lib/python2.7/dist-packages/rql/nodes.py", line 639, in get_type
    if lhstype == rhstype and not 'Date' in lhstype:
  TypeError: argument of type 'CubicWebEntitySchema' is not iterable

* add support for TZDatetime
* properly raise on unsupported addition (e.g. date+date)
* dates can be added to Interval, not Time

Closes #3248236

Capturing the latter only results in an empty StringIO.

The original patch for bug #1190458 broke tests in CubicWeb. The patch
has now been amended to fix the broken paths (namely, replacing the 'in'
tests with appropriate 'is_equivalent' loops).

These tests are adapted from CubicWeb's own test suite, especially those
that test FTIRANK() on sqlite (the function exists but is replaced by a
no-op).

Related to #1167312

Mostly in comments and defunct tools.
Related to #1167312

WARNING: This is an API break

Among other things we no longer use repr() for String constants, which
means they consistently get quoted with double quotes instead of a mix
of single and double quotes.

Closes #1190507

Related to #1167312

- there is no distinction between PyInt and PyLong anymore
- module initialization changed a bit

Related to #1167312

The existing implementation relies on hash returning different values
for objects that compared equal.  This is horribly wrong.  Instead, stop
implementing comparison, and use the is_equivalent method explicitly.

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.