Users should not force insensitive all joined limits, as well
warn on case sensitive searches

Because of historical reasons, RT's searches were marked as case
sensitive in RT::SearchBuilder::Limit, although callers often expected
them to be case insensitive.

Mixing case sensitive and case insensitive searches by the same column
causes problems on Pg and Oracle -- especially as the case-sensitivity
of the search and any indexes may cause them to not be used.

This adds code to catch, for specific columns, cases where CASESENSITIVE
is not explicitly specified, and throws a warning.
Force group names to be case-insensitive
case insensitive search by Groups.Domain
catch and fix case sensitive searches by CF name
Make queue names case-insensitive
Force user names and email addresses to be case-insensitive
handle case sensitivity in manually generated SQL
use LimitToUserDefinedGroups method instead of Limit
Merge branch '4.2/warn-on-case-sensitive-searches'