renamed to mail.channel.

At this point no model has been renamed; only files have been moved.
n mail, mail_group files have been renamed to mail_channel. The
website_mail_group addon has been renamed to website_mail_channel.
Some internal references have been updated (templates, linked files).

The module system needs to know the dependencies of a given module
before executing the function.  This is why the dependencies were
defined once in an array, and then were described one more times in the
call to require.

But a trick can simplify this: the boot function can parse the string
representation of the module and extract the calls to require from it.
It is more work for the processor, but it leads to simpler module
definitions.

website.snippet: The methods described in javascript will be called automatically from the data-method_name = value on li snippets options. The methods are called in the order relative to children of xml (eg: <li data-method1=value1> ... <li data-method2=value2> ... </ li>, the method1 is then called method2). Methods receive two arguments: type (over, click, reset) and value. data-snippet-id-option becomes data-snippet-id. Several xml options can use the same data-snippet-id.

add a new gallery snippet

convert website_sale to the new option system

Plus it fails because `event` is not defined nor passed there (e.g. in Firefox)