classes: fix class style problems found by b071cd58af50 This makes test-wireprotocol.py work on Python 2.4

check-code: fix class style checking (with tests) - old-style classes were only checked for one-letter class names - add check for new-style classes with empty parent class, because this is not available in Python 2.4

tests: ignore inotify extension in test-duplicateoptions.py The inotify extension is only available on linux and setup.py will not install it on other platforms - but it will of course always be there in the source. test-duplicateoptions.py tried to load most extensions (including inotify if available). When the local uninstalled Mercurial was used it would thus always load the inotify extension and cause a warning on unsupported platforms. The inotify extension is not relevant for this test, so now we explicitly ignore it.