fix marker interaction in a backward incompatible way

[RonnyPfannschmidt]

problem:
markers transfer between subclasses and base classes due to marker trasnfer mutating objects belonging to base classes from subclasses

related issues:

• skipif mark from parametrize hides module level skipif mark #1540
• skipif + parametrize not skipping tests #1296
• pytest.mark.parametrize fails with lambdas #1111
• request.node.get_marker('name') returns None for markers applied in classes #902
• create a useful pytest.mark.test taking ideas from nose.tools.istest #899
• pytest_generate_tests doesn't play with pytest.mark.parametrize #896
• remove named marker attributes and collect markers in items #891
• py.test can't xfail tests parametrized with callable objects #750
• pytest.mark.parametrize string-based parameter list doesn't handle single element tuples #719
• markers stains on all related classes #568
• marker transfer incompatible with inheritance #535
• Markers as functions #277

[nicoddemus]

I'm thinking we want to fix this for 3.0?

[RonnyPfannschmidt]

im not sure we can, the more i look into markers and how we use them, the more bugs and edge-cases show up

[The-Compiler]

So... is this 4.0 material then?

[RonnyPfannschmidt]

fixed in #3317