Show smarty E-notices when in debug mode

[colemanw]

Overview

Shows php notices (e.g. "undefined variable") when the system is in debug mode.

Before

Notices always hidden.

After

Let the games begin.

[civibot]

(Standard links)

• If this is your first pull-request for CiviCRM, please browse CONTRIBUTING.md for information about the development and testing processes.
• If you are reviewing this pull-request, you may wish to consult the test sites and the Review Standards (long template, short template).