Fix walkhelper on windows. The ''seen'' dictionary stores paths in canonical form, so the walkhelp must also provide paths in that form, otherwise the changed files are listed twice.

disallow '\n' and '\r' in tag names add a test for disallowed characters in tag names

Merge with http://hg.omnifarious.org/~hopper/mercurial

Convert all classes to new-style classes by deriving them from object.