First pass at making MissingView/MissingLayout exceptions show all
paths.

Showing all the paths a template file could be located help expose
developers to the view path cascade and helps ensure we don't tell
people the wrong place to put a view file.

Refs #3712
Cleanup missing view/layout errors.

Fix formatting issues and make path listings correct.
Remove dead code.

The list of paths is now output on the default error page, we don't need
to make an educated guess here anymore.
Filter out core paths from missing view/layout errors.

End developers shouldn't be dropping files in /lib/Cake so lets not tell
them to.
Merge pull request #3744 from markstory/2.6-missing-views

2.6 Improve missing view error pages