This changes the use of the || operator when setting the default of the
user attribute if the key does not exist to #fetch. This will make sure
that if false is passed in as the value it will still fail and use the
default setting.
This also adds constants to define and array and a hash of symbols which
is iterated over to set the users attributes.
FEATURE: context is not emailed if we previously emailed you the post
FEATURE: site setting to enable_watch_new_topics , false by default.
When enables users can elect to watch everything by default
FIX: Custom email subjects (x quoted you in [title], x replied to [title])
was removed, this broke email grouping. TBD, include info in footer somehow
FIX: topic user specs were messy, reduce side effects