GitLab

- add a `callable_deprecated` warning on html_escape
- use xml_escape function instead of html_escape function

- We're not overriding an inherited function, `_` parameter is useless
- We're not using line parameter in the function body, `line` is useless
- Add `argument_removed` deprecation warning for the users who may still use this function.

Testing py3 and check-manifest
Note that test suite still uses logilab-pytest generative tests, so we have to use logilab-pytest here.

Drop debian packaging from python sdist.
Add missing files from doc/ and announce.txt

Add python_requires and python3 only classifiers.
This avoid pip on python2 downloading a non python2 compatible package.

We're going to drop python2 support.
Drop rpm python packaging util someone make a python3 rpm packaging.

We now ship the full test directory with the Python package.

This allows to run the test suite during Debian package build, and add
autopkgtest support that will run testsuite against the installed
package.

Update Debian packaging to current best practices:

    - Use dh-python and pybuild buildsystem and simplify debian/rules
      accordingly.
    - Use PYBUILD_NAME instead of debian/*.install files.
    - Update minimum Python versions to supported ones.
    - Update Standards-Version to 4.3.0.

Tests are currently disabled as they are not shipped in source package.