Fix not working former_ids. Add support for "Invalid accounts". Now when id from former_ids tries to create a profile "This account is invalid." error message is displayed. Compare emails in lower cases to prevent changing User email to the same email with different character casing (needs some more testing). Patch by: Pawel Solyga

"""
Code used in a couple of places to work with the current thread's environment.
Current users include i18n and request prefix handling.
"""

try:
    import threading
    currentThread = threading.currentThread
except ImportError:
    def currentThread():
        return "no threading"