Prevent html errors when FormField::create_tag('meta') is called from $MetaTags() so
```
<meta name="generator" content="SilverStripe - http://silverstripe.org"></meta>
```
becomes
```
<meta name="generator" content="SilverStripe - http://silverstripe.org" />
```
Add all void elements to list
API Substitute Zend_Locale with Locale / NumberFormatter
API Substitute Zend_Date with IntlDateFormatter
API Added DBTIme::Nice12, FormatFromSettings
API Added Short() method to DBDate / DBTime / DBDatetime
API Add Date::getTimestamp()
API Added setSubmittedValue api for FormField
API Add second arg to base FormField::setValue()
API Major refactor of i18n into component data parts
API Implement Resettable interface to reset objects between tests
ENHANCEMENT Changed DBField::create_field return type to `static` to support better type hinting
ENHANCEMENT i18nTextCollector supports __CLASS__
