*Title: New AutoConvertOnSave setting

*Documentation:
A new setting in template.ini is added - CharsetSettings:AutoConvertOnSave -
which will automatically convert your templates to the HTTPCharset as set in
i18n.ini whenever you save a template that you edit in the administration
interface. This is done so that eZ Publish does not need to spend more time
converting this template to the HTTPCharset every time. The default is
"enabled".

In case there was a charset header ( {*?template charset=utf-8?*} ) in the
template, it will be modified accordingly and if there was no charset header
present, one will be added.