Fix regression in test_langs.php

Commit 78cee358 added file Web.config to plugins and lang folder.
test_langs.php treated the file as a plugin folder and a language file.
Merge branch 'fix13-test_langs' of github.com:atrol/mantisbt into atrol-fix13-test_langs
Fix #17510: regression in test_langs.php
Add functionality to allow blocking of specific email address domains
Handle email validation and parsing consistently across mantis, by utilising the HTML 5 Standard.

Fixes the following Issues:

0017275: email matching within Mantis should follow html5 standard
0017276: Allow the ability to block specific domains from registering users within Mantis
0017279: Handling of email addresses within Mantis is not consistent
0017280: Email address validation function strips characters

Follow Up work to Consider:

0017277: Allow use of wildcards when limiting email domain names
0017278: Allow ability to block email domains via wildcard

In addition, we should consider whether to add the html to define an 'email pattern' on the email address registration field so that we can utilise browser verification of the email address.
Or would this currently require a change in the current DOCTYPE we set
Add functionality to support wildcard matching when limiting and/or blocking email domain names

Fixes the following Issues:

0017277: Allow use of wildcards when limiting email domain names
0017278: Allow ability to block email domains via wildcard
Add a new event EVENT_VALIDATE_EMAIL_ADDRESS that allows a plugin to define additional checks for email

This event files within email_is_valid function at the following point:

AFTER:
a) we check whether validate email is on
b) after we check whether allow_blank_email config is on
c) after we call FILTER_SANITIZE_EMAIL from php to strip invalid characters
d) after we check the email regex against the html 5 standard

but before we check against limit_email_domains/blocked_email_domains/do MX record checking

Therefore email addresses hitting this validation hook will already have had some basic sanity checking done against them.

The result of the hook is one of 3 things:
true - i.e. allow and no further checks
false - i.e. reject
null ==> perform our other internal validation checks.

I'm assuming this would mainly be used to implement REJECTION hooks.

If it was to be used to return true, care would have to be taken to consider the impact on the remaining checks i.e. limit/allow email domains and MX record checking


Fixes:

0017284: Allow Plugins to implement their own email Validation checks
Add Event Logging for email validation
Upgrade PHPMailer to 5.2.8
Fix typo
Add example documentation covering use of wildcard matching