bookmarks: disallow bookmarks named 'tip', '.', or 'null'
This makes bookmarks reject the same reserved names as tags and branches.
# When --inotify is activated, help output and config changes:
test-debugcomplete
test-empty
test-fncache
test-globalopts
test-help
test-hgrc
test-inherit-mode
test-qrecord
test-strict
# --inotify activates de facto the inotify extension. It does not play well
# with inotify-specific tests, which activate/deactivate inotify at will:
test-inotify
test-inotify-debuginotify
test-inotify-dirty-dirstate
test-inotify-issue1208
test-inotify-issue1371
test-inotify-issue1542
test-inotify-issue1556
test-inotify-lookup