generalized version of create_user()
determining subscribers by subscription_ids

--HG--
extra : amend_source : 174a16b538fbf636e2d65b06edec27842ac42430
Merged thomaswaldmann/moin-2.0 into default
Merged thomaswaldmann/moin-2.0 into default
Merged thomaswaldmann/moin-2.0 into default
admin traceback emails
Merged thomaswaldmann/moin-2.0 into default
EmailHandler get log level
add subscription constants
subscription validator
indexing subscriptions
user subscription functionality
Merged thomaswaldmann/moin-2.0 into default
determining subscribers by subscription_patterns
update subscription validator

1. Use of constants in the error message
2. Check NAMEPREFIX value validity
3. Validate NAMERE pattern
4. Change the 'invalid value' error message
change simple occurences of subscribed_items to subscriptions
subscribed_pages migration from moin1.9
fix usages of subscribe(), unsubscribe() and is_subscribed_to() methods in views and templates
pass item object as argument to render template
merged