[REM] models: remove `_columns`

addons/mrp/report/mrp_production_templates.xml

addons/survey/tests/test_survey.py

openerp/addons/base/tests/test_acl.py

openerp/addons/base/tests/test_base.py

openerp/addons/base/tests/test_expression.py

openerp/addons/test_inherit/tests/test_inherit.py

openerp/addons/test_new_api/tests/__init__.py

openerp/addons/test_new_api/tests/test_field_conversions.py

openerp/addons/test_new_api/tests/test_new_fields.py

openerp/fields.py

openerp/models.py

openerp/osv/__init__.py

openerp/osv/expression.py

openerp/osv/fields.py

openerp/report/report_sxw.py

openerp/tests/addons/test_translation_import/models.py

openerp/tools/convert.py