Remove ClassifySQLOperation
Be consistent about ->{looking_at_foo} vs ->{_sql_looking_at}{foo}

The code was inconsistent, setting both in different places, and
checking them similarly inconsistently.  Settle on the _sql_looking_at
form, which is the one which was more relevant internally.
Merge remaining functions from Tickets_SQL.pm into Tickets.pm
The Join method ignores SUBCLAUSE; deprecate _SQLJoin in favor of Join
Restrict SUBCLAUSE lexically during parsing, and switch to simple Limit

Now that Limit functions as every other DBIx::SearchBuilder class, it is
no longer necessary to call SUPER::Limit.  Additionally, the use of the
confusing _SQLLimit method can be avoided by lexically setting the
default subclause during parsing in FromSQL.  This obviates the need to
remember the difference between the two methods.

Deprecate the old _SQLLimit for future removal.
Remove unused Restriction-related methods

These methods are unused and do not function as expected.  As part of
de-emphasizing the Restrictions interface, remove them.
TicketAliases was removed when TicketSQL came in, in f4ef4bb
->{'rows'} has not been used since DBIx::SB 1.27
Merge branch '4.2/tickets-cleanup'

Conflicts:
	lib/RT/Tickets_SQL.pm
        507e226 (from 4.0-trunk) changed %lcfields to %LOWER_CASE_FIELDS.
        Port that commit to lib/RT/Tickets.pm like the rest of Tickets_SQL.pm.