Fix IN replacement in virtual fields for MYSQL.
doc block update.
Simplify test
Correct test
Show stack trace for fatal errors if xdebug is loaded.
Merge pull request #5053 from dereuromark/master-xdebug

Show stack trace for fatal errors if xdebug is loaded.
Merge pull request #5021 from dereuromark/master-mysql

Fix IN replacement in virtual fields for MYSQL.
Merge branch 'master' into 2.6
Merge branch '2.6' of github.com:cakephp/cakephp into 2.6