Fix re: and glob: patterns in .hgignore (reported by Brad Schick) relglob: and relre: were already detected for a long time, so I kept this undocumented functionality, especially as it was already tested in test-hgignore.

# should print nothing
# should print ? b/x
? b/x
# should print A b/x
A b/x
# should forget b/x
forgetting b/x
# should print nothing