used for conditional plugin loading
- fix case where xfail is defined at module/class level
- fixes and improvements to docs, correct links to plugins
- use new skip facilities here and there
--HG--
branch : trunk
* separate all tests from plugins
* simplify implicit inclusion of plugins under test
* have test_initpkg perform direct checks instead of yielding tests
* fix example tests for 3k
--HG--
branch : trunk